We use the Chinese Remainder Theorem to solve systems of congruence equations.
Tips
history
Origin in 《孙子算经》 (Sūnzǐ Suànjīng, ~3rd–5th century CE), which posed: a number divided by 3 leaves 2, by 5 leaves 3, by 7 leaves 2 — find it. Generalized by Qin Jiushao (秦九韶) in 1247. Western mathematicians later named it after its Chinese origin.
memory
Parse it as 中国 (Chinese) + 剩余 (remainder) + 定理 (theorem) — exactly the English calque.