expression, godan verb (-u)
the figures add up; the calculation comes out right
Used when checking accounts or calculations; literally means 'the abacus matches'.
何度計算してもそろばんが合わない。
No matter how many times I calculate, the figures don't add up.
expression, godan verb (-u)
Figurative extension: the business or deal makes financial sense.
この商売はそろばんが合わないからやめたほうがいい。
This business doesn't pay, so you'd better quit.