Memory and Mental Calculation World Records

Comments? Corrections? New Records? Please contact us at info@recordholders.org


Links:

Memory Books,

World Memory Championships (WMSC),

Memoriad,

Mental Calculation World Cup,

Memory Sports Database,

World Memory Statistics,

Mind Sports Worldwide
portal site for memory sports

Mental Calculation Mailing List,

Mnemonics,

Memo Camp

Communities:

Yahoo Club "Memorysports"

Books:


Learn to Remember by Dominic O'Brien, record holder in a lot of memory categories
ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk

Memory Pack by Andi Bell, another memory record breaker
ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk

MORE BOOKS...

Memorising Pi


digits record holder year Pi and Pi Memory Links:

www.pi-world-ranking-list.com
The world ranking list for memorising Pi

worldpifederation.org
World Pi Federation

www.acc.umu.se/~olletg/pi
Olles' Pi Page with the 1000 club and the 100 club,
open only for Pi-enthusiasts who can recall 100 / 1000 digits from memory

Pi Memorama
a place for pi-memorizing enthusiasts

4,200,000,000 decimal digits of Pi

Pi Links
great link page

Books about Pi:



David Blatner: the Joy of Pi
The best books for people interested
in Pi who are not mathematicians
ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk


Pi : A Source Book
historical articles about Pi,
requires skill in higher
mathematics
ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk


Peter Beckman: History of Pi
a historical book
(out of date when it comes
to computer calculations.)
ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk


Jorg Arndt, Christoph Haenel:
Pi-Unleashed, with computer
programs on CD-ROM,
requires skill in higher
mathematics
ORDER from amazon.com

A book about Pi record breaker Rajan Mahadevan: Memory Search By A Memorist

...and if you have read enough about Pi consider this book:
e: The Story of a Number



511 David Richard Spencer (Canada) ?
930 Nigel Hodges (Great Britain) 1973
1,111
Fred Graham (Canada)
1973
1,210 Timothy Pearson (Great Britain) 1973
1,505 Edward C. Berberich (USA) 1974
3,025 Michael John Poultney (Great Britain) 1974
4,096 Simon Plouffe (Canada) 1975
5,050 Michael John Poultney (Great Britain) 1977
6,350 David Sanker (USA) 1978
10,000 David Sanker (USA) 1978
10,625 David Fiore (USA) 1979
11,944 Hans Eberstark (Austria) 1979
15,151 Hideaki Tomoyori (Japan) 1979
15,186 Creighton Carvello (Great Britain) 1979
20,000 Hideaki Tomoyori (Japan) 1979
20,013 Creighton Carvello (Great Britain) 1980
31,811 Rajan Mahadevan (India) 1985
40,000 Hideaki Tomoyori (Japan) 1987
42,195 Hiroyuki Goto (Japan) 1995
67,890
Chao Lu (China)
2005

new record claims (not yet confirmed) by Akira Haraguchi (Japan): 83431 on 1 July 2005 and 100,000 on 4 October 2006

In 1998, Yip Swe Chooi (Malaysia) recited 60,000 digits of Pi with only 44 errors. Sim Pohann (Malaysia) recited 67,053 digits with only 15 errors on 14 April 1999.
Two more special records for memorising Pi can be found here.

Memorising Random Numbers

Most Digits Memorised in 2 / in 4 Seconds

See extra page with details about this record

Most Binary Digits Memorised in 3 Seconds

See extra page with details about this record

Most Binary Digits Memorised in One Minute


84 Jan Formann (Denmark) 1999 light bulb
93 Jan Formann (Denmark) 2000 light bulb
96 Ralf Laue (Germany) 2002
107 Ralf Laue (Germany) 2002 light bulb
129 Ralf Laue (Germany) 2003
140 Gunther Karsten (Germany) 2003
148 Ralf Laue (Germany) 2003
154 Lukas Amsüss (Austria) 2003
156
Gunther Karsten (Germany) 2005

162
Gunther Karsten (Germany) 2005
240
Itay Avigdor (Israel) 2006

Note: The records with the "light bulb" icon were achieved using light bulbs (on or off) which makes the record more difficult.
On several occasions, the  record for 5 minutes (see below) was superior to the record for one minute, so in fact the record holder for 5 minutes should be regarded as the record holder for one minute as well. Itay Avigdor's record has been set in front of witnesses, but not at a location open to the general public.
New record reported (not yet confirmed): 264 by Jayashimha Ravirala (India).

National records not mentioned in the above table:
Indonesia: 216, Dominic Brian Hindarto, 2010
Germany: 207, Christian Schäfer, 2010
India: 132, Nischal Narayanam, 2009
China: 100 (in 42.7 seconds), Jia Xiaoxia, 2009 light bulb

Most Binary Digits Memorised in 5 Minutes


600 Gunther Karsten (Germany) 2002
780
Ben Pridmore (Great Britain) 2004
795
Ben Pridmore (Great Britain) 2007
930
Ben Pridmore (Great Britain) 2008
975
Johannes Mallow (Germany) 2013
1016
Ola Kåre Risa (Norway)
2013
1080
Johannes Mallow (Germany) 2013

Spoken Numbers (Spoken at a Rate Of One Digit Every Second)


74 Dario Donatelli (USA) year not known
128
128
Dominic O'Brien (Great Britain)
Jan Formann (Denmark)
2001
2002
140
Andi Bell (Great Britain) 2003
188
Clemens Mayer (Germany)
2005
202
Gunther Karsten (Germany) 2008
240
Simon Reinhard (Germany)
2010
300
Wang Feng (China) 2011
318
Jonas von Essen (Sweden)
2013
364
Johannes Mallow (Germany) 2013

Spoken Numbers (Spoken at a Rate Of One Digit Every 2 Seconds)

Three attempts: The first one with 100 numbers, the second one with 200 numbers and the third one with 400 numbers


100 Dominic O'Brien (Great Britain) 1993
142 Dominic O'Brien (Great Britain) 1994
200 Dominic O'Brien (Great Britain) 1995
228 Andi Bell (Great Britain) 1997
333 Andi Bell (Great Britain) 1999
400
(perfect score)
Gunther Karsten (Germany) 2000

Memorisation of Written Numbers (1 Minute)

no errors allowed

68
Gunther Karsten (Germany) 2005
72
Oddbjørn By (Norway)
2006
100
Ramón Campayo (Spain) 2006
102 Gunther Karsten (Germany) 2007

Memorisation of Written Numbers (100 Digits)

no errors allowed

1:22.3 min
Gunther Karsten (Germany) 2002
0:50.1 min
Ramón Campayo (Spain) 2006

Memorisation of Written Numbers (5 Minutes)

Contestants recall the number by writing it down. No mistake in each line of 40 digits scores 40 points. However, one mistake reduces the score for that row to 20, the second mistake reduces the score for that row to zero.


132 Dominic O'Brien (Great Britain) 1993
157 Dominic O'Brien (Great Britain) 1994
182 Dominic O'Brien (Great Britain) 1995
200 Dominic O'Brien (Great Britain) 1996
240 Dominic O'Brien (Great Britain) 1997
314 Yu Zhang (USA) 1999
316 Dominic O'Brien (Great Britain) 2000
324
Jan Formann (Denmark) 2003
333
Ben Pridmore (Great Britain) 2005
396
Andi Bell (Great Britain) 2007
405
Johannes Mallow (Germany)
2008
480
Wang Feng (China)
2010
500
500
Wang Feng (China)
Johannes Mallow (Germany)
2011
2012
501
Johannes Mallow (Germany) 2013

Memorisation of Written Numbers (15 Minutes)

Contestants recall the number by writing it down. No mistake in each line of 40 digits scores 40 points. However, one mistake reduces the score for that row to 20, the second mistake reduces the score for that row to zero.


700 Clemens Mayer (Germany) 2006
819
Ben Pridmore (Great Britain) 2008
912
Johannes Mallow (Germany) 2013
937
Johannes Mallow (Germany) 2013

Jan Formann (Denmark) memorised 760 digits at the Memory World Cup 2004. The rules at this event were slightly different from other memory contests.

Memorisation of Written Numbers (30 Minutes)

Random numbers are presented in rows of 40 digits. Scoring is tabulated by row: one point for each digit. However, one mistake reduces the score for that row to 20, the second mistake reduces the score for that row to zero.

832 Jan Formann (Denmark) 2001
989 Gunther Karsten (Germany) 2002
998 Gunther Karsten (Germany) 2003
1004 Astrid Plessl (Austria) 2003
1040
Clemens Mayer (Germany)
2005
1160
Gunther Karsten (Germany) 2007
1264
Johannes Mallow (Germany)
2009
1284
Johannes Mallow (Germany) 2010
1320
Johannes Mallow (Germany) 2011
1400
Simon Reinhard (Germany)
2012

Memorisation of Written Numbers (1 Hour)

Random numbers are presented in 25 rows of 40 digits. Scoring is tabulated by row: one point for each digit. However, one mistake reduces the score for that row to 20, the second mistake reduces the score for that row to zero.


900 Dominic O'Brien (Great Britain) 1993
1080 Dominic O'Brien (Great Britain) 1994
1140 Dominic O'Brien (Great Britain) 1995
1392 Dominic O'Brien (Great Britain) 1996
1620 Andi Bell (Great Britain) 1997
1820 Andi Bell (Great Britain) 2000
1840 Yip Swe Chooi (Malaysia) 2002
1914 Gunther Karsten (Germany) 2003
1920
Jan Formann (Denmark) 2003
1949
Gunther Karsten (Germany) 2005
2080
Su Ruiqiao (China)
2009
2280
Wang Feng (China)
2010
2660
Wang Feng (China) 2011

Memorisation of Binary Numbers (30 Minutes)

Random binary numbers are presented in rows of 30 digits. Scoring is tabulated by row: one point for each digit. However, one mistake reduces the score for that row to 20, the second mistake reduces the score for that row to zero.


1002 Dominic O'Brien (Great Britain) 1993
1296 Dominic O'Brien (Great Britain) 1994
1470 Dominic O'Brien (Great Britain) 1995
1926 Dominic O'Brien (Great Britain) 1996
2745 Yu Zhang (USA) 1999
2889 Gunther Karsten (Germany) 2002
2970 Gunther Karsten (Germany) 2003
3180 Gunther Karsten (Germany) 2003
3705
Ben Pridmore (Great Britain)
2004
3710
Ben Pridmore (Great Britain) 2006
3915
Ben Pridmore (Great Britain) 2007
4140
Ben Pridmore (Great Britain) 2007

Memorising Words / Text

The most impressive feat for learning words - memorising 23200 words within 72 hours - was reported by Ramón Campayo (Spain). Unfortunately, there is no written documentation about his records, so that they cannot be regarded as "official" records for this list.

Memorisation of previously unpublished text (15 Minutes)

(This category is no more held at memory contests.)


345 points Astrid Plessl (Austria)
2003

Memorisation of Random Words (15 Minutes)

Random words are presented in columns of 25 words. Scoring is tabulated by column: one point for each word. However, one mistake reduces the score for that column by half, the second mistake reduces the score for that column to zero.


125 Dominic O'Brien (Great Britain) 1993
153 Dominic O'Brien (Great Britain) 1995
155 Dominic O'Brien (Great Britain) 1997
174 Andi Bell (Great Britain) 1998
182 Andi Bell (Great Britain) 2002
199
Boris-Nikolai Konrad (Germany)
2004
214
Boris-Nikolai Konrad (Germany) 2006
227
Boris-Nikolai Konrad (Germany) 2007
255
Boris-Nikolai Konrad (Germany) 2008
280
Boris-Nikolai Konrad (Germany) 2009
300
Simon Reinhard (Germany) 2010

Memorising Playing Cards

Most cards memorised (inter-shuffled packs)

The record is for the greatest number of packs of 52 cards all shuffled together, memorised and recalled. The contestant is allowed to view the cards once only.

Rules:

Two independent witnesses/invigilators, persons of some standing in the community, must be present during the entire attempt. If a wrong card is called and this is corrected immediately and spontaneously without prompting then this would not count as an error. The maximum number of errors acceptable is half of one percent of the total number of cards involved, rounded up to the nearest whole number.

The time taken to memorise the cards and to recall them should be recorded but are not essential requirements of the record.



Packs Cards Record Holder Year Errors
30 1560 George Uhrin (USA) 1989 2
35 1820 Dominic O'Brien (Great Britain) 1990 2
36 1872 Frost McKee (USA) 1992 8
40 2080 Dominic O'Brien (Great Britain) 1993 1
52 2704 David Farrow (Canada) 1996 6
54 2808 Dominic O'Brien (Great Britain) 2002 8
59
3068
David Farrow (Canada) 2007
1
The story behind this record - written by Dominic O'Brien - can be read HERE.

10 Minutes Memorisation of Several Packs of Cards

Contestants are given 10 minutes to memorise as many of 12 packs of cards (52 cards each) as they can. No mistakes in a pack of cards scores 52 points, one mistake scores 26 points and more than one mistake scores zero points.

156 Gunther Karsten (Germany) 2001
220 Gunther Karsten (Germany) 2002
258
Gunther Karsten (Germany) 2006
312
Ben Pridmore (Great Britain) 2006
364
Ben Pridmore (Great Britain) 2008

30 Minutes Memorisation of Several Packs of Cards

832 Ben Pridmore (Great Britain)
2007
884
Ben Pridmore (Great Britain) 2008

1 Hour Memorisation of Several Packs of Cards

Contestants are given one hour to memorise as many of 12 packs of cards (52 cards each) as they can. No mistakes in a pack of cards scores 52 points, one mistake scores 26 points and more than one mistake scores zero points.


624 Dominic O'Brien (Great Britain) 1995
710 Dominic O'Brien (Great Britain) 1996
1170 Andi Bell (Great Britain) 1997
1197 Andi Bell (Great Britain) 2002
1404
Ben Pridmore (Great Britain)
2006
1456
Ben Pridmore (Great Britain) 2010

Speed Record : A Single Pack

The record is for the fastest time to memorise a single pack of 52 shuffled playing cards with no errors.


149 s Dominic O'Brien (Great Britain) 1991
125 s Jonathan Hancock (Great Britain) 1991
55.62 s Dominic O'Brien (Great Britain) 1992
44.62 s Mamoon Tariq Khan (Pakistan)
1993
43.59 s Dominic O'Brien (Great Britain) 1994
42.01 s Tom Groves (Great Britain) 1994
38.29 s
Dominic O'Brien (Great Britain) 1996
34.03 s Andi Bell (Great Britain) 1998
32.9 s
Andi Bell (Great Britain) 2004
32.13 s
Ben Pridmore (Great Britain) 2005
31.03 s
Ben Pridmore (Great Britain) 2006
26.28 s
Ben Pridmore (Great Britain) 2007
24.97
Ben Pridmore (Great Britain) 2009 VIDEO
21.90 s
Simon Reinhard (Germany)
2010
21.19 s
Simon Reinhard (Germany) 2011

Speed Record two decks

The basic rules are the same one as for one deck. Each pack should be shuffled seperatly, the decks should NOT be mixed. In every step, two cards together should be turned - one from the first deck, the second one from the other deck. Everytime the contestants can see two cards.

The records


3:37 min Dominic O'Brien (Great Britain) 2001

Memorising Names and Faces (15 Minutes)

Faces are presented to the contestants in a certain order with corresponding names underneath. They are then presented in a new order without names. Contestants mark names on new sheets. One point is awarded for each correct forename, one point for each surname.


100 Jonathan Hancock (Great Britain) 1993
140 Jonathan Hancock (Great Britain) 1994
156 Andi Bell (Great Britain) 2002
167.5
Andi Bell (Great Britain) 2004
170
Clemens Mayer (Germany)
2005
181
Clemens Mayer (Germany) 2006
195
Boris-Nikolai Konrad (Germany) 2009
201
Boris-Nikolai Konrad (Germany) 2010

Note: The record for international names and faces - the category that is now used in memory competitions - is 181 by Simon Reinhard (Germany), achieved in 2013.

Memorising Historic Dates (5 minutes)

36
36
Miroslav Koblic (Czech Republic)
Gunther Karsten (Germany)
2001
2001
38 Gunther Karsten (Germany) 2001
43 Gunther Karsten (Germany) 2001
50
50
Andi Bell (Great Britain)
Gunther Karsten (Germany)
2002
2002
51 Gunther Karsten (Germany) 2003
60
60
Ben Pridmore (Great Britain)
Gunther Karsten (Germany)
2003
2004
80
Ben Pridmore (Great Britain) 2004
96
Ben Pridmore (Great Britain) 2006
99
Johannes Mallow (Germany)
2007
110.5
Johannes Mallow (Germany) 2008
118
Johannes Mallow (Germany) 2009
120
Johannes Mallow (Germany) 2010
132
Johannes Mallow (Germany) 2011

Memorising Abstract Images (15 minutes)

199 Gunther Karsten (Germany) 2006
228
Gunther Karsten (Germany) 2006
244
Gunther Karsten (Germany) 2007
276
Gunther Karsten (Germany) 2008
318
Gunther Karsten (Germany) 2009
350
Gunther Karsten (Germany) 2010
365
Johannes Mallow (Germany) 2010
385
Johannes Mallow (Germany) 2011
434
Johannes Mallow (Germany) 2012
440
Johannes Mallow (Germany) 2013
492
Johannes Mallow (Germany) 2013

Playing Games From Memory While Blindfolded

Chess

Claims in this category have been put into doubt by rumours that the master had the games written down, or that large number of opponents agreed to resign after a few nominal moves, for example. The following table contains the record that were accepted by the chess community.

A wealth of information about blindfold chess can be found in the book "Blindfold Chess" by Eliot Hearst und John Knot and the web site www.blindfoldchess.net.


games player year result
1
1
Sa'id Bin Jubair
Josef Tchelebi (Greece)
~690
970

2 Buzzecca (Saracen)
1265
3
3
3
3
3
3
Al-Jami
Giovanni Girolamo Saccheri (Genoa)
Francois André Danican Philidor (France)
Lionel Kiesertzky (France)
William Lewis (Great Britain)
Louis Charles de la Bourdonnais (France)
1331
1667
1783
1846



4
4
Lionel Kiesertzky (France)
Louis Paulsen (Germany)
1851
1857
+3=0-1
+2=1-1
5 Louis Paulsen (Germany) 1857 +4=1-0
7
Louis Paulsen (Germany) 1858
7=0-0
8 Louis Paulsen (Germany) 1858
10 Louis Paulsen (Germany) 1858 +9=1-0
15
15
Louis Paulsen (Germany) (disputed)
Joseph Blackburne (Great Britain)
1859
1876

16
16
Johannes Hermann Zukertort (Poland)
Harry Nelson Pillsbury (USA)
1876
1900
+12=3-1
+11=4-1
17
Harry Nelson Pillsbury (USA) 1900
+10=5-2
20 Harry Nelson Pillsbury (USA) 1897 +14=5-1
21 Harry Nelson Pillsbury (USA) 1902 +3=11-7
(very strong opponents)
22 Harry Nelson Pillsbury (USA) 1902 +17=4-1
24 Richard Réti (Czechoslovakia) 1919 +12=9-3
25 Gyula Breyer (Hungary) 1921 +15=7-3
26 Alexander Alekhine (France) 1924 +16=5-5
(very strong opponents)
28 Alexander Alekhine (France) 1925 +22=3-3
29 Richard Réti (Czechoslovakia) 1925 +20=7-2
30 George Koltanowski (Belgium) 1931 +20=10-0
32 Alexander Alekhine (France) 1933 +19-9=4
34 George Koltanowski (Belgium) 1937 +24=10-0
40 Miguel Najdorf (Argentina) 1943 +36=1-3
45 Miguel Najdorf (Argentina) 1947 +39=4-2
46
Marc Lang (Germany) DETAILS 2011
+25=19-2

Draughts


games player year result
8 Wim Huisman (Netherlands) 1955 +5=1-2
10 Ton Sijbrands (Netherlands) 1982 +9=1-1
12 Ton Sijbrands (Netherlands) 1986 +11=1-0
14 Ton Sijbrands (Netherlands) 1987 +12=1-1
15 Ton Sijbrands (Netherlands) 1991 +13=2-0
18 Ton Sijbrands (Netherlands) 1993 +14=4-0
20 Ton Sijbrands (Netherlands) 1999 +17=3-0
22
Ton Sijbrands (Netherlands) 2002
+17=5-0
24
Ton Sijbrands (Netherlands) 2004
+20=4-0
25
Ton Sijbrands (Netherlands) 2007
+21=4-0
27
Erno Prosman (Niederlande) 2008
+15=8-4
28
Ton Sijbrands (Netherlands)
2009
+18=7-3

In 1947, Newell W. Banks (USA) played blindfold for 4 hr per day for 45 consecutive days, winning 1331 games, drawing 54 and losting only two, while playing six games at a time.

Rubik's Cube

see extra page with details about this record

Mental Calculation: Addition

Addition of 100 single-digit numbers

Rules:
The general rules for calculating records apply.

  1. This record is for the fastest time for an individual to add together 100 single-digit numbers.
  2. The record is a test of straightforward mental calculation. The calculator should perform the calculation in his/her head without the aid of any other person and without using a calculating machines, computers, etc. nor may the calculator write the numbers down.
  3. The 100 numbers (0-9) to be added together should be randomly selected by computer immediately prior to the calculation and should be displayed to the calculator on a computer screen, board, screen or similar. The numbers should ideally be presented on the screen in rows of, for example, five or ten digits.
  4. The calculator must see all the numbers simultaneously - numbers may not appear one after another on a screen etc. for the calculator.
  5. The calculator should write down the answer to the calculation.
  6. The timing begins when the 100 numbers become visible to the competitor and ends at the end of writing the answer.
  7. In some cases, the calculator may dictate the answer - then the timing ends as the calculator finishes dictating the answer.
  8. Two stopwatches should be used: it would be appreciated these stopwatches record in minutes and seconds and tenths of a second rather than hundredths of an hour. At the end of the attempt the time should be taken as an average of the two watches.

32.57 s R. H. Frost (Great Britain) 1977
19.23 s Alberto Coto (Spain) 1999

Note: New record claim (not yet verified): 18.8 sec by Lam Yee Hin (China) in 2002

Addition of  ten 10-digit numbers

(10 tasks for adding ten 10-digit numbers correctly)
The general rules for calculating records apply.

Alberto Coto (Spain) 5:50 min
30 October 2004 at the Mental Calculation World Cup in Annaberg-Buchholz (Germany)
Jorge Arturo Mendoza Huertas (Peru)
5:36 min
27 April 2005 at the National University Peru
Alberto Coto (Spain) 4:35 min
1 July 2008 at the Mental Calculation World Cup at the University of Leipzig (Germany)
Alberto Coto (Spain) 4:26 min
1 July 2008 at the Mental Calculation World Cup at the University of Leipzig (Germany)
Ramon Abella Villa (Spain)
4:22.6 min
21 June 2009 at the Impossibility Challenger Games in Dachau (Germany)
Ramon Abella Villa (Spain) 4:02.9 min
21 June 2009 at the Impossibility Challenger Games in Dachau (Germany)
Alberto Coto (Spain) 3:42 min
6 June 2010 at the  Mental Calculation World Cup in Magdeburg (Germany)
Marc Jornet Sanz (Spain)
3:19.4 min
23 September 2010 at the Mathematics Faculty of the University of Valencia (Spain)
Naofumi Ogasawara (Japan) 3:11 min
30 September 2012 at the Mental Calculation World Cup in Gießen (Germany)
Akshita Shailesh Shah (India)
3:06.9 min
23 November 2012 at the Memoriad 2012 at Belconti Resort Hotel in Antalya (Turkey)
Granth Rakesh Thakkar (India)
3:06.3 min
23 November 2012 at the Memoriad 2012 at Belconti Resort Hotel in Antalya (Turkey)
Naofumi Ogasawara (Japan) 2:51.1 min
24 November 2012 at the Memoriad 2012 at Belconti Resort Hotel in Antalya (Turkey)

There is also a detailed statistics page with the world rankings and national records.

Mental Calculation: Multiplication

Johann Martin Zacharias Dase (Germany, 1824-1861) multiplied two 20 digit numbers in 6 minutes, two 48 digit numbers in 40 minutes and two 100 digit numbers in 8 3/4 hous in 1861.
He also multiplied two 8 digit numbers in 54 seconds. These records are historically accepted, although they were not achieved under modern rules.

In 1980, Shakuntala Devi (India) was reported to have multiplied two 13-digit numbers in 28 sec. This record was accepted by the Guinness Book of Records, but later they added the comment "Some experts on calculating prodigies refuse to give credence to the above - largely on the grounds that it is so vastly superior to the calculating feats of any other invigilated prodigy."

The Limca Book of Records (India) accepts this record as well as "Buzan's Book of Mental Records" which comments: "We respectfully point out that Mrs Devi has been invigilated at a number of times, has appeared on numerous live television shows, performing 'new' calculations based on the works of various mathematics professors, and has consistently performed at the level indicated in her record-breaking performance. We support Mrs Devi in her natural excellence, and hope that researchers will increasingly realise that their amazement and amusement should lie not in the outstanding excellence of any human mental performance, but in the rarity of similar performances."

Note: One of the factors she had to multiply ended in 0, so that in fact she multiplied a 12 digit number with a 13 digit number.

Multiplication of two 5- or 8-digit Numbers

Rules:
The general rules for calculating records apply.

  1. This record is for the fastest time for an individual to multiply two five-digit / eight-digit numbers.
  2. Ten tasks have to be solved without a single error. The clock does not stops between the taske.
  3. The record is a test of straightforward mental calculation. The calculator should perform the calculation in his/her head without the aid of any other person and without using a calculating machines, computers, etc. nor may the calculator write the numbers down.
  4. The numbers to be multiplied together should be randomly selected by computer immediately prior to the calculation and should be displayed to the calculator on a computer screen, board, screen or similar.
  5. The calculator should write down the answer to the calculation. If the answer is written down, this can be done left-to-right, right-to-left or in any arbitrary order.
  6. The timing begins when the two numbers become visible to the competitor and ends at the end of writing the answer.
  7. In some cases, the calculator may dictate the answer - then the timing ends as the calculator finishes dictating the answer.
  8. Two stop watches should be used: it would be appreciated these stopwatches record in minutes and seconds and tenths of a second rather than hundredths of an hour. At the end of the attempt the time should be taken as an average of the two watches.

world records: five-digit numbers
Jan van Koningsveld (Germany) 3:06 minutes
25 November 2005 at Berufsbildenden Schule I in Emden
Marc Jornet Sanz (Spain) 1:42 minutes
5 June 2010 at the  Mental Calculation World Cup in Magdeburg
Marc Jornet Sanz (Spain) 1:16 minutes
23 September 2010 at the Mathematics Faculty of the University of Valencia (Spain)
world records: eight-digit numbers
Mohammed Seghir Saïd (Algeria) 13:00 minutes
6 March 2006 at youth hostel Tizi-Ouzou
Alberto Coto (Spain) 11:44 minutes
1 July 2008 at the  Mental Calculation World Cup in Leipzig
Alberto Coto (Spain)  8:25 minutes
1 July 2008 2008 at the  Mental Calculation World Cup in Leipzig
Marc Jornet Sanz (Spain)
 4:56 minutes
6 June 2010 at the  Mental Calculation World Cup in Magdeburg
Marc Jornet Sanz (Spain)  4:29.3 minutes
7 June 2010 at the  Mental Calculation World Cup in Magdeburg
Freddis Reyes Hernández (Cuba)
4:28.8 minutes
23 November 2012 at the Memoriad 2012 at Belconti Resort Hotel in Antalya (Turkey)
Freddis Reyes Hernández (Cuba) 3:54.1 minutes
23 November 2012 at the Memoriad 2012 at Belconti Resort Hotel in Antalya (Turkey)

There is also a detailed statistics page with the world rankings and national records.
Books about Mental Calculation:

The Mental Calculator's Handbook

The Mental Calculator's Handbook, written by the world champions Robert Fountain and Jan van Koningsveld

ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk


Calculating Without Instruments

Dead Reckoning - Calculating Without Instruments

ORDER from amazon.com
from the UK:
ORDER from amazon.co.uk

How To Calculate Quickly

How to calculate Quickly

ORDER from amazon.com
from the UK:
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Mental Calculation: Extracting Roots

Calculating the Square Root of a Six-Digit Number
13th root of a 100 digit number
23rd root of a 200 digit number
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Mental Calculation: Calendar From Memory

20 Dates From One Century
All Dates From One Year
Most Dates From 1600-2100 Within One Minute
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Mental Calculation: Solving Linear Equation Systems

Selçuk Soner Akgül (Turkey) solved ten linear equation systems (each with three equations and three variables, and each having exactly one integer solution) in 10:21.77 minutes on 20 October 2010 at the 9th Mathematics Symposium at Karadeniz Technical University, Turkey.

Mental Calculation: Factorizing Numbers

20 random five-digit numbers (which were not prime numbers) were given to Willem Bouman (Netherlands). He found all prime factors of them in 13:39 minutes on 22 December 2010 at the Delft University of Technology, Netherlands. Willem's tutorial for finding the factors of large numbers can be found here.

Mental Calculation: Division

Ten problems for dividing a 10-digit number by a 5-digit number (no remainders left) have to be solved.

Willem Bouman (Netherlands) 6:07 min
18 October 2011 in Eindhoven
Amit Garg (India)
5:45 min
15 March 2012 at Baybridge Decision Technologies in Annapolis (USA)


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