also: ひゃくマスけいさん
100-square calculation; grid-based arithmetic drill
A learning method using a 10×10 grid for repetitive practice of basic arithmetic (addition, subtraction, multiplication, etc.), often used in Japanese elementary schools to build speed and accuracy.
Every morning, class starts after doing 100-square calculations.
Practicing multiplication with 100-square calculations makes mental arithmetic faster.
Standard spelling using ます in hiragana; widely recognized in educational contexts.
Variant spelling with マス in katakana; also seen in practice.
From 百 (hundred) + ます (square, cell) + 計算 (calculation), referring to the 100 cells in the 10×10 grid used for the drill.