GMCA YouTube page here has a variety of videos: matches, informational videos, interviews, demonstrations, and short clips.

A basic overview of the world of Japanese soroban is available here. GMCA also offers a Japanese soroban rating test simulator here.

Practice simulators available here and competition app available here.

If you are looking for practice guides, WorldMentalCalculation includes guides for approaching certain competition-style formats.

Registration Open for Season 4 Now

〰️

Registration Open for Season 4 Now 〰️

Global Mental Calculators Association:

Mental Calculation League

TT

Two Seasons per year: Spring/Summer and Fall/Winter

Match videos available here and on GMCA Youtube page.

Season 3 began in July 2025! Here are links to: Results, Standings, and Season Statistics.

Please visit “Mental Calculation League” section to Register for Season 4 and for more information.

Practice “league simulator,” as well as other calculation simulators, are available here. The Calculation League app —with FAQ and an instructional video — is available here.

Jeonghee Lee
Aaryan Shukla
Wenzel Gruss
Master Lee Teaching

Board Members