also: くきょほう
casting out nines
A mathematical technique for verifying arithmetic by checking remainders modulo nine. Domain-specific term.
Casting out nines is used to check addition and multiplication.
Alternate reading; きゅうきょほう is more common.
From 九 (nine) + 去 (remove) + 法 (method). The term is a direct translation of the English 'casting out nines'.