Author: 悅璃乃 (えりの)(jpdong@hpu.edu.kg)

The Number Guessing Game

When three walk together, seventy is rare; Twenty-one branches of plum blossoms on five trees; Seven sons reunite at half-moon; Subtract one hundred and five, the answer appears.

——— (Ming Dynasty) Cheng Dawei, Suanfa Tongzong (General Collection of Arithmetic Methods)

The first time I became interested in the “Chinese Remainder Theorem” was simply because its name stood out so uniquely among all theorems. Its solution method, “Qin Jiushao’s Dayan Qiuyi Shu (The Art of Seeking One)”, is also an exceptionally elegant and sacred name that can spark boundless imagination in a high school student. This sacred piece of mathematics comes from the Sunzi Suanjing (The Mathematical Classic of Master Sun) from the Northern and Southern Dynasties—not the military strategist Sunzi who led troops during the Spring and Autumn period, but a mathematician surnamed Sun from that later era. The famous “chickens and rabbits in the same cage” problem also originates from this book.

Published on 2026-07-25 at 閑時茶話, last modified on 2026-07-25