Chinese remainder theorem

https://en.wikipedia.org/wiki/Chinese_remainder_theorem

http://planetmath.org/ChineseRemainderTheorem

Sunzi's original formulation: x ≡ 2 (mod 3) ≡ 3 (mod 5) ≡ 2 (mod 7) with the solution x = 23 + 105k where k ∈ ℤ