CALENDAR CALCULATION WORLD RECORDS There are three different categories: one year, one century and dates from 1600 to 2100. More about calendars (and an algorithm to calculate the day of the week) can be found at www.calendarhome.com. Please keep us informed about new record attempts.

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One Century

The Rules

1. The record is for finding the correct days of the week from 20 random dates from the whole century.
2. 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.
3. 20 dates of the current century must be randomly selected by computer or by taking lottery tickets, but not by writing down dates at the referee's direction or dates of birth. Every day of the century must have the same chance to be chosen (including the 29^th February in every 4th year).
4. The dates must be written down to a list. The record breaker must not look at this list until the record starts. Alternatively, a computer can be used for displaying the tasks and also for taking the time needed by the competitor.
   
5. After the referee has started the attempt and two independent stop watches have been started, the record breaker finds the days of the week for all dates in the list.
6. The method of identifying the dates is optional but the following methods may be considered:
• A system of buttons or buzzers may be employed with, for example, button 1 representing Monday, button 2 Tuesday and on on - the competitor presses the appropriate button to record his/her answer for each date in succession. Only one attempt may be made to identify each date.
• The competitor may write down his/her answers to each date in order. Only one answer may be made to identify each date.
• The competitor may record his/her answers electronically. Only one answer may be made to identify each date.
7. Two stopwatches should be used. The timing begins when the dates become visible to the competitor and ends at the end of writing / speaking the last answer. At the end of the attempt the time should be taken as an average of the two watches.
8. A new record can be set only if there are NO ERRORS. (This must be checked when the record attempt is over.) If the record breaker speaks the days of the week instead of writing them down, the record attempt must be recorded on a tape.

World Records

(new records will be accepted for 20 dates only!)

03-06-1993 Dany Sirejean (France)              18 dates / 48 sec
03-05-1997 Luc Rouleau (Canada)                20 dates / 35 sec
09-11-2003 Matthias Kesselschläger (Germany)   20 dates / 24.94 sec
31-10-2005 Yusnier Viera Romero (Cuba)         20 dates / 23.2 sec
31-10-2005 Yusnier Viera Romero (Cuba)         20 dates / 19.8 sec
06-11-2005 Matthias Kesselschläger (Germany)   20 dates / 17.9 sec
12-03-2010 Jan van Koningsveld (Germany)       20 dates / 17.42 sec
12-03-2010 Jan van Koningsveld (Germany)       20 dates / 17.03 sec
12-03-2010 Jan van Koningsveld (Germany)       20 dates / 16.61 sec
12-03-2010 Jan van Koningsveld (Germany)       20 dates / 16.16 sec
 5-06-2010 Freddis Reyes Hernandez (Cuba)      20 dates / 13.47 sec
 7-06-2010 Freddis Reyes Hernandez (Cuba)      20 dates / 13.30 sec
 7-06-2010 Freddis Reyes Hernandez (Cuba)      20 dates / 12.72 sec
 4-12-2010 Yusnier Viera Romero (Cuba)         20 dates / 10.76 sec
 4-12-2010 Yusnier Viera Romero (Cuba)         20 dates / 10.44 sec
 4-12-2010 Yusnier Viera Romero (Cuba)         20 dates /  9.37 sec
 4-12-2010 Yusnier Viera Romero (Cuba)         20 dates /  9.04 sec
 4-12-2010 Yusnier Viera Romero (Cuba)         20 dates /  8.05 sec

PC-Program to find random dates

If you want to break this record, you can find a program for generating date lists here.

One Year

The Rules

1. The record is for finding the correct days of the week from all 365 or 366 dates from the current year.
2. 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.
3. All dates of the current year must be written down in random order (selected by computer or by taking lottery tickets, but not by writing down dates at the referee's direction). The record breaker must not look at this list until the record starts. Alternatively, a computer can be used for displaying the tasks and also for taking the time needed by the competitor.
4. After the referee has started the attempt and two independent stop watches have been started, the record breaker finds the days of the week for all dates in the list.
5. The method of identifying the dates is optional but the following methods may be considered:
• A system of buttons or buzzers may be employed with, for example, button 1 representing Monday, button 2 Tuesday and on on - the competitor presses the appropriate button to record his/her answer for each date in succession. Only one attempt may be made to identify each date.
• The competitor may write down his/her answers to each date in order. Only one answer may be made to identify each date.
• The competitor may record his/her answers electronically. Only one answer may be made to identify each date.
6. Two stopwatches should be used. The timing begins when the dates become visible to the competitor and ends at the end of writing / speaking the last (365^th or 366^th) answer. At the end of the attempt the time should be taken as an average of the two watches.
7. A new record can be set only if there are NO ERRORS. (This must be checked when the record attempt is over.) If the record breaker speaks the days of the week instead of writing them down, the record attempt must be recorded on a tape.

World Records

26-06-1982 Ilse Kirsch (Germany)              431 sec
28-01-1983 Ilse Kirsch (Germany)              348 sec
28-04-1983 Ilse Kirsch (Germany)              309 sec
28-04-1983 Ilse Kirsch (Germany)              293 sec
29-03-1984 Ilse Kirsch (Germany)              248 sec
16-11-1984 Ilse Kirsch (Germany)              230 sec
05-09-1985 Ilse Kirsch (Germany)              227 sec
08-10-1994 Ralf Laue   (Germany)              222 sec
09-11-2003 Matthias Kesselschläger (Germany)  218 sec
06-11-2005 Matthias Kesselschläger (Germany)  214 sec
 4-12-2010 Yusnier Viera Romero (Cuba)        191.4 sec
24- 9-2011 Yusnier Viera Romero (Cuba)        170.2 sec
31-10-2015 Yusnier Viera Romero (USA)         161.3 sec
27-01-2018 Yusnier Viera Romero (USA)         150.4 sec

1600-2100, one minute

The Rules

The record is for the greatest number of days of the week correctly identified from random dates in one minute.

1. Dates between 1 January 1600 and 31 December 2100 are selected at random by computer immediately prior to the challenge.
2. The dates should be presented to the competitor(s) either on a sheet of paper. Alternatively, a computer can be used for displaying the tasks and also for taking the time needed by the competitor.
3. Dates should be shown digitally, thus 14 June 1947 should appear as 14-6-1947 or 14/6/1947 or similar.
4. If a screen is used, all the dates should appear simultaneously to the competitor(s) on the screen. Whatever system is used to record answers (see below), all the dates are shown one after another simultaneously to the competitor - if dates are shown one after another the speed at which each competitor works would be artificially slowed.
5. The competitor(s) should identify which day of the week the dates were. This must be done in the order in which the dates are listed.
6. One minute is allowed for the challenge. An experienced timekeeper should keep the time with an accurate stopwatch. Alternatively, a computer system can do the timing.
   
7. The timing begins when the dates become visible to the competitor(s).
8. The method of identifying the dates is optional but the following methods may be considered:
• A system of buttons or buzzers may be employed with, for example, button 1 representing Monday, button 2 Tuesday and on on - the competitor presses the appropriate button to record his/her answer for each date in succession. Only one attempt may be made to identify each date.
• The competitor may write down his/her answers to each date in order. Only one answer may be made to identify each date.
• The competitor may record his/her answers electronically. Only one answer may be made to identify each date.
9. Only correct answers count towards the total. If more than one incorrect answer is given by a competitor his/her attempt is nullified.
10. the name of the person making the attempt should be given, along with the date and place.

World Records

09-04-1999 Ralf Laue      (Germany)            14
03-10-1999 Stephan Gruber (Germany)            19
26-11-1999 Gert Mittring  (Germany)            20
27-10-2002 Stephan Gruber (Germany)            22
09-11-2003 Matthias Kesselschläger (Germany)   32
30-10-2004 Matthias Kesselschläger (Germany)   33
31-10-2005 Yusnier Viera Romero (Cuba)         42
06-11-2005 Matthias Kesselschläger (Germany)   45
18-12-2006 Yusnier Viera Romero (Cuba)         53
18-12-2006 Yusnier Viera Romero (Cuba)         56
 2-11-2008 Jan van Koningsveld (Germany)       56
 5-12-2009 Yusnier Viera Romero (Cuba)         59
12-03-2010 Jan van Koningsveld (Germany)       63
12-03-2010 Jan van Koningsveld (Germany)       66
12-03-2010 Jan van Koningsveld (Germany)       69
12-03-2010 Jan van Koningsveld (Germany)       70
 5-06-2010 Freddis Reyes Hernandez (Cuba)      73
 5-06-2010 Freddis Reyes Hernandez (Cuba)      74
 7-09-2010 Jan van Koningsveld (Germany)       78
 4-12-2010 Yusnier Viera Romero (Cuba)         91
 4-12-2010 Yusnier Viera Romero (Cuba)         93
24-10-2015 Jan van Koningsveld (Germany)       96
31-10-2015 Yusnier Viera Romero (USA)         103
31-10-2015 Yusnier Viera Romero (USA)         111
 9-11-2016 Jay Baldiya Jain (India)           125
27-01-2018 Yusnier Viera Romero (USA)         132
27-01-2018 Yusnier Viera Romero (USA)         140
 9-03-2924 Yusnier Viera Romero (USA)         148
 9-03-2924 Yusnier Viera Romero (USA)         159