also: くきょほう
noun
casting out nines
A mathematical technique for verifying arithmetic by checking remainders modulo nine. Domain-specific term.
九去法は、足し算や掛け算の検算に使われる。
Casting out nines is used to check addition and multiplication.
From 九 (nine) + 去 (remove) + 法 (method). The term is a direct translation of the English 'casting out nines'.