計算
けいさん · keisan · JLPT N3 · noun
calculation
🧮 計 count aloud (言 speech + 十 ten) + 算 bamboo counting rods = calculation
計 combines 言 (words) and 十 (ten): counting out loud up to ten. 算 has 竹 (bamboo) on top because people once calculated with bamboo counting rods, the ancestor of the abacus. Counting plus reckoning gives you calculation.
算 — bamboo 竹 + abacus 具 (eye 目 + two hands 廾)
Originally depicted counting with bamboo rods on an abacus-like device. The top 竹 (bamboo) refers to the bamboo counting sticks used in ancient Chinese arithmetic, while the bottom shows hands manipulating them. The meaning broadened from 'to count' to 'to calculate' or 'to plan'.