The 17th edition of the Junior Mental Calculation World Championship was held in Bielefeld, 04–07 September, as organized by Caroline Merkel since 2008 [official JMCWC website]. 99 competitors from Algeria, Bosnia, Bulgaria, Czechia, Egypt, France, Germany, India, Japan, Lebanon, Mexico, Panama, Serbia, 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. It also provides a platform for students from all around the world to break boundaries and represent their country internationally.
[Note: this information should be correct, but if you notice anything that needs correcting, please let me know 😊]
Under-12s age category
The top three places for the youngest age category were secured by first-time medal-winners, including the first medal for Turkmenistan. Two more participants scored 2400+ points, which is an outstanding achievement!
- 1st: 🇮🇳 Arshika Gupta (2545)
- 2nd: 🇩🇿 Mohamed Imad Eddine Benyahia (2488)
- 3rd: 🇹🇲 Mekan Nurgeldiyev (2477)
All of the medal-winners scored higher than last year’s top score of 2416.
Under-15s age category
The “Juniors 2” age category was won by Andrej Živanović, who improved on his score from last year by nearly 10%! This was also the largest age category this year, with nearly 50 participants. Of these, 7 scored 2500+ points, including 🇦🇪 Madhav Krishna Seshadri Sumanth who was again close to the medals with 2600+ points.
- 1st: 🇷🇸 Andrej Živanović (2817)
- 2nd: 🇮🇳 Achyuttam (2695)
- 3rd: 🇩🇿 Akram Abdelkader Belmahi (2629)
Under-20s age category
The “Seniors” category had a maximum score of 3061, including 440 points on the seven pages of Surprise tasks. It was won by Kaloyan Geshev who remarkably only made two errors on the entire paper!
- 1st: 🇧🇬 Kaloyan Geshev (3045)
- 2nd: 🇮🇳 Abhilakshya Arora (2965)
- 3rd: 🇩🇿 Walid Ksentini (2853)
As always, there were many other excellent scores, including 🇯🇵 Mako Inokawa whose huge score of 2784 earns another 4th-place finish, and 🇮🇳 Parth Garg who improved his score by nearly 400 points since his last JMCWC medal.
Alumni category
The “Seniors Plus” category is exclusive for a limited number of alumni invited by the organizers due to their involvement in the event.
- 1st: 🇮🇳 Radhika Maheshwari (2691)
- 2nd: 🇱🇧 Mohammed El-Mir (2583)
- 3rd: 🇮🇳 Deepak Nagar (2178)
These scores are particularly impressive as these participants typically have many responsibilities in further education or their career, and have to balance their JMCWC preparation with everything else!
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 whose square is 15100996 [3886]
- On what day of the week was 28-Mar-1764 [Wednesday]
This year, there were some new categories of calculation for participants to solve:
- Approximate multiplications and divisions
- HCF and LCM
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 seven JMCWC alumni:
- George Lane (creator of the Pegasus mental calculation simulators, and 5-time gold medallist at the MSO)
- Elke Kuge
- Willem Bouman
- Freddis Reyes
- Ralf Laue (creator of the Mental Calculation World Cup)
- Max Weber
- Johanna van Koningsveld
- Joshua Spring
- Walid Henni
- Mohammed El-Mir
- Radhika Maheshwari
- Deepak Nagar
- 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 a number-themed treasure hunt around Bielefeld!
Congratulations to all participants who attended the event—and thank you for contributing to make these days a positive and enjoyable experience.
Hectoc Competition:
Dinah and Oliver Spring 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 more than 100 participants in total. Each participant’s score is the number of Hectocs solved correctly in 15 minutes, from a selection of 100 questions.
JMCWC Contestants:
- 1st: 🇧🇬 Daniil Dimitrov (71)
- joint-2nd: 🇩🇿 Nouha Bouzidi (69) & 🇩🇿 Mohamed Iyed M’Ghozzi (69)
Adults and other Hectoc participants:
- joint-1st: 🇧🇬 Georgi Georgiev (61) & 🇩🇪 Joshua Spring (61)
- 3rd: 🇩🇿 Lofti Habib Ellah Seddiki (35)
World Record in Sums of Squares
During the closing ceremony, 🇧🇬 Kaloyan Geshev successfully beat the world record in expressing ten 5-digit numbers as the sum of squares, with a new time of 38 seconds.
As an example, 12345 = 110² + 15² + 4² + 2² [a maximum of four squares in the sum is permitted]
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?
- Do you know a young person talented in Mathematics or mental calculation?
- Do you train students in mental calculation, abacus/soroban or Mathematics?
Here are some ways you can get started:
- This page has information about the 2026 paper (which was similar to previous years’ papers)
- Try some of the medium-difficulty techniques, such as multiplication, fractions and exact cube roots of 6-digit numbers. When you know the best techniques and start practising, you too can calculate quickly like JMCWC alumni!
- 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 early in September 2027. 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!