そろばんが合あう

expression, godan verb (-u)

the figures add up; the calculation comes out right

Used when checking accounts or calculations; literally means 'the abacus matches'.

• 何なん度ど計けい算さんしてもそろばんが合あわない。

  No matter how many times I calculate, the figures don't add up.

expression, godan verb (-u)

to be profitable; to pay

Figurative extension: the business or deal makes financial sense.

• この商しょう売ばいはそろばんが合あわないからやめたほうがいい。

  This business doesn't pay, so you'd better quit.