The Junior Mental Calculation World Championship returned to Bielefeld, 04–06 October, as organized by Caroline Merkel since 2008 [official JMCWC website]. Around 80 competitors from Algeria, Bulgaria, the Czech Republic, Egypt, Germany, Hungary, India, Japan, Mexico, Panama, Qatar, Serbia, South Africa, Turkmenistan and the UAE qualified and attended—some for their first time, while others have attended for many years.
Although this is a “junior” competition, several of the participants have won medals in international competitions open to adults—such as the MSO online and the MCWC 2024. This 2025 competition was another record-breaking year in terms of the amount of high scores from well-prepared participants from around the world!
New groups attended this year from Egypt, Panama and Turkmenistan. Two of the competitors from Turkmenistan became the first ever (as far as I can recall) to get 2000+ points in their first JMCWC competition!
[Note: this information should be correct, but if you notice anything that needs correcting, please let me know 😊]
Under-12s age category
The youngest age category—”Junior 1″—was won by Wissal Firdaousse Douidi, who achieved 2nd place last year, and was one of many Algerians with great scores this October! The maximum mark available was 2614 points.
- 1st: 🇩🇿 Wissal Firdaousse Douidi (2416)
- 2nd: 🇩🇿 Mohamed Iyed M’Ghozzi (2361)
- 3rd: 🇮🇳 Mihika Samir Bole (2279)
All of the medal-winners scored higher than last year’s top score of 2225, and will by next year compete in the “Juniors 2” category, when they are 12+ years old.
Under-15s age category
The “Junior 2” age category was won by Andrej Živanović, who further improved on his score from last year. The maximum score was 2842. The other medal-winners helped Algeria collect over half of the medals for this year’s contest!
- 1st: 🇷🇸 Andrej Živanović (2576 points)
- 2nd: 🇩🇿 Mouncif Seddiki (2415 points)
- 3rd: 🇩🇿 Chahinez Boumaiza (2324 points)
Several other competitors made this category very competitive with scores over 2000 points!
Under-20s age category
The “Senior” category had a maximum score of 2965 and was extremely competitive this year! It was won by Kaloyan Geshev in his first year in the Seniors category, where he mostly finished after 100 (out of 120) minutes, with 98% of the paper solved correctly.
- 1st: 🇧🇬 Kaloyan Geshev (2911)
- 2nd: 🇩🇿 Walid Ksentini (2681)
- 3rd: 🇿🇦 Stiaan Scheepers (2663)
Walid improved his score by 100+ points, and Stiaan by 200+ points, to achieve these results. The following participants obtained scores above 2000 points: 🇩🇿 Manar Benmastora (2098); 🇩🇿 Anwar Khelif (2405); 🇩🇿 Malek Adala (2463); 🇩🇿 Nouha Bouzidi (2472); 🇯🇵 Mako Inokawa (2587) and 🇦🇪 Raghav Krishna Seshadri Sumanth (2595).
Format of the Championship
The main contest is a 2-hour paper that includes a variety of mental math categories, such as:
- 726446 + 294855 [1021301]
- Find the integer that squares to 15100996 [3886]
- On what day of the week was 28-Mar-1764 [Wednesday]
Here are some resources that may help students (and their teachers) to prepare for the championship.
The day before the competition, there were workshops for all the participants, provided by mental calculation experts including JMCWC alumni:
- George Lane (creator of the Pegasus mental calculation simulators, and 5-time gold medallist at the MSO)
- Elke Kuge
- Willem Bouman
- Martin Drees
- Freddis Reyes
- Max Weber
- Johanna van Koningsveld
- Joshua Spring
- Walid Henni
- Daniel Timms (me—author of this website)
The weekend was also very social, where both the children and their accompanying adults could meet others from around the world, for dinners, workshops, cultural performances, and even a trip to a cake factory!
Congratulations to all participants who attended the event—and thank you for contributing to make these days a positive and enjoyable experience.
Hectoc Competition:
The Spring family organized a Hectoc competition, where participants had to produce the number 100 from a string of six digits (1–9) using the standard Hectoc rules. For example:
123456: 100 = 1 + (2 + 3 + 4) × (5 + 6)
224459: 100 = –2 + (2 × 44) + 5 + 9
There were 114 participants in total. Each participant’s score is the number of Hectocs solved correctly in 15 minutes, from a selection of 80 questions.
JMCWC Contestants:
- 1st: 🇧🇬 Daniil Dimitrov (60)
- 2nd: 🇧🇬 Kaloyan Geshev (57)
- 3rd: 🇩🇿 Mohamed Iyed M’Ghozzi (56)
Adults and other Hectoc participants:
- 1st: 🇧🇬 Georgi Georgiev (64)
- 2nd: 🇩🇪 Joshua Spring (45)
- 3rd: 🇩🇿 Walid Henni (36)
Sponsorship for the JMCWC was generously provided by the Andreas Mohn Foundation.
Get Involved Next Year
Would you be interested in competing in this event, or do you know a young person talented in Mathematics or mental calculation? Here are some ways you can get started:
- This page has information about the 2025 paper (which was similar to the previous years’ papers)
- Try some of the medium-difficulty techniques, such as multiplication, fractions and exact cube roots of 6-digit numbers. With practice, your speed can improve dramatically!
- Contact Caroline Merkel (she organizes this event) for any communication about registering. This includes collaboration with regional events.
- Contact me (or other trainers) for any questions about training mental calculation.
- Look out for updates about future competitions. Next year’s competition is likely to be in September. Official confirmation and full details will be provided later by the JMCWC organizers when the details are ready. I hope to see you there 😊
It would be great to see even more countries joining next time!