Mental Calculation World Cup Results 2018

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Last weekend was the 8th Mental Calculation World Cup, organised by Ralf Laue and attended by possibly the strongest-ever field of participants. Congratulations to everyone involved!

More details about the competition are available at its official website maintained by Ralf Laue – including the full 2018 results tables.

Individual Events:

The competition contained 10 rounds:

  • Calendar: calculating the weekday for random dates between 1600-2099
  • Addition: of sums of ten 10-digit numbers
    • 1st: Jeonghee Lee (S Korea) – 33 sums in seven minutes (30 points after deductions)
    • 2nd: Tomohiro Iseda (Japan) – 31 (27)
    • 3rd: Osako Takuma (Japan) – 25 (23)
  • Multiplication: of products of two 8-digit factors (e.g. 12345678 x 98765432)
  • Square roots: to 8 significant figures of accuracy
    • 1st: Tomohiro Iseda (Japan) – 48 in ten minutes (42 points after deductions)
    • 2nd: Hiroto Ihara (Japan) – 47 (40)
    • 3rd: Mohammad El-Mir – 25 (22)
  • Challenge task: several questions of this type, announced a few months previously
    • 1st: Hiroto Ihara (Japan) – 66 correct in ten minutes
    • 2nd: Jeonghee Lee (S Korea) – 63
    • 3rd: Tomohiro Iseda (Japan) – 61
    • only Osako Takuma (40), Mohammad El-Mir (27) and Wenzel Grüß (22) above 6!
  • Surprise #1: calculate remainders when various large numbers are divided by a small number – e.g. the remainder when 12345678901234 is divided by 37
    • Hiroto Ihara (Japan) achieved the highest score
  • Surprise #2: calculate integers from a fraction with 3 divisors – e.g. 1481900/(25*73*14) (answer is 56)
    • Tomohiro Iseda (Japan) and Wenzel Grüß (Germany) achieved the top score
  • Surprise #3: determine (to one significant figure) the distance light travels in certain periods of time – e.g. if light travels at 299792 kilometers per second, how many meters does it travel in 71 minutes?
    • Martin Drees (Germany) achieved the top score
  • Surprise #4: evaluate a sum of (possibly negative) integer fractions – e.g. 4/3 – 11/12 + 5/4 + 17/51 – 1/20 (answer is 1.95)
    • Samuel Engel (USA) achieved the top score
  • Surprise #5: identify as many incorrectly-answered 9-by-9-digit multiplications as possible – e.g. 123456789 x 987654321 = 12193263134234823 is incorrect (with a point deducted for every false alarm!)
    • Wenzel Grüß (Germany) and Jean-Jacques Bruyant (France) achieved the top score

Combined Awards:

Overall Winners: for the combined score of all 10 events

  • 1st: Tomohiro Iseda (Japan) – 757.18 points
  • 2nd: Hiroto Ihara (Japan) – 663.54 points
  • 3rd: Wenzel Grüß (Germany) – 593.80 points

Most Versatile Calculator: for the combined score of the 5 surprise tasks

  • 1st: Wenzel Grüß (Germany) – 461.17 points
  • 2nd: Tomohiro Iseda (Japan) – 333.91 points
  • 3rd: Samuel Engel (USA) – 330.01 points

Memoriad Trophy: for the combined score of the 4 standard tasks

  • 1st: Tomohiro Iseda (Japan) – 330.85 points
  • 2nd: Jeonghee Lee (S Korea) – 261.68 points
  • 3rd: Marc Jornet Sanz (Spain) – 257.62 points

Melik Duyar was present to award free flights to Dubai for Memoriad 2020 to these three competitors, where they have the opportunity to compete again at mental calcuation, memory and speed reading.

 

Record Attempts:

Marc Jornet Sanz, Jeonghee Lee and Freddis Reyes Hernández all battled to set a new world record for 8-by-8-digit multiplication, which was held by Freddis until 2016 and Jeonghee since then.

Marc improved the record 3 times on Saturday, then Jeonghee retook the record. Finally on Sunday, Marc set the current world record of 2 minutes, 49.85 seconds. This is an average of 17 seconds for each multiplication!

Jeonghee Lee also set a huge new world record at 10-by-5-digit integer division with ten problems correctly solved in 53.20 seconds!

Daniel Timms (me) also set a new British record for calendar calculations with 59 dates calculated in 1 minute.

 

Other Announcements:

The competition was generously sponsored by the Andreas Mohn Foundation and hosted by Phaeno – a Science Museum in Wolfsburg, Germany.

Unfortunately some of the invited competitors were unable to attend the event for various reasons – but hopefully will be competing again in a future event

4 thoughts on “Mental Calculation World Cup Results 2018”

  1. Surprise #2: calculate integers from a fraction with 3 divisors – e.g. 1481900/(25*73*14) (answer is 56)

    sorry, correct answer is
    58

    greetings from Wenzi
    (I got it right then)

  2. Hello Daniel! It was indeed a great competition and a great first time for me especially that I had applied for the event only 3 to 4 weeks before it started. Will hopefully do better in 2020. Congratulations to all participants that have reached this stage and to all the winners!

  3. Hi Daniel, thank you so much for your site. It’s a competent overview with all relevant facts from a real insider, who knows what he is talking about. Great.

  4. Hi Daniel, I am Marc, the participant from the competition. The World Cup was a nice experience. And thank you for being a witness in my multiplication world record!
    Keep training with calendar dates. You’re very near to reaching one date per second!
    Regards and we keep in touch.

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