JMCWC Resources

The Junior Mental Calculation World Championship 2024 will take place in September 2024 in Bielefeld 🇩🇪.

The official website of the JMCWC has the official information about the program, rules (PDF), and contact details in case you have any questions about the competition. 📧

This page contains various resources for participants, so that you can prepare effectively. I hope it will help you! 😊

Updates:

  • 24 August: updated Simulators
  • 27 August: link to method for exact cube roots
  • 31 August: official JMCWC website has updated Rules document (no major changes since 2018)
  • 02 September: link to method for exact square roots

Changes between 2023 → 2024 Competitions

The following pages now use a vertical format: Integer Additions; and Mixed Additions and Subtractions. Please refer to the new Simulators.

There are minor changes to the number and difficulty of some pages.

Approximately 100 extra points are now available in the Surprises. This is to encourage participants to have more variety in their training, rather than only using the Simulators. There are at least 6 pages pages of Surprises, and these are scattered throughout the paper.

JMCWC Simulator

The exam contains 20+ pages of standard questions, plus a few pages of Surprises.

George Lane has prepared Simulators of the standard questions for 2024, which you can download here to see what the exam will look like. You will need Excel, or an open-source alternative such as LibreOffice.

Note: these Simulators were updated on 24-Aug-2024. They now have the correct (more difficult) Ratios page.

The Surprises use similar skills, but they are not in any simulator, because they are a surprise 😉

Instructions for Simulator

The simulators randomly regenerate new questions every time you open or edit the file. The answers are written in white, and you can reveal them simply by changing the answer column to your choice of colour, for example red.

Be caseful not to edit or close the file between solving the questions and revealing the answers, otherwise you won’t be able to check them! On LibreOffice, changing the colour also regenerates all the questions, which is unhelpful. However, you can turn off auto-calculation to avoid this problem.

The print ranges are already set. but they can still be checked before printing. If anything looks bad, just go to Page Layout & Margins, and set the page to print on 1 tall by 1 wide.

As an alternative to printing, you can simply write the answers on paper and then check them against the answers in the document.

General Advice

Generally, it is recommended that participants start at the beginning of the paper and work through systematically. However, most participants will not finish the paper, so it may be a good strategy to skip questions or sections that you find difficult, so you have time for your favourite types of question and to check the Surprises.

It is strictly forbidden to write any method or intermediate calculations anywhere during the test. All calculation must be done mentally, and only the answers may be written.

Mental Calculation Techniques & Training Tools

Some of the categories are best solved using advanced techniques, that you might not learn at school! Here are some resources and tools for the most difficult categories. Many participants in the competition will only know the basics—they won’t know most of these extra methods!

Calendar Dates

Multiplication

Division

Fractions

Square Roots & Deep Roots

Sums of Squares

  • Online Training Tool: makes practice more efficient, as it checks your answer automatically. Sums of squares questions typically have multiple possible correct answers!

Good luck—see you in Bielefeld! 🎉