noun
abacus calculation; counting on the abacus
Literal use: performing arithmetic with an abacus. Often implies a meticulous, step-by-step reckoning.
祖父は今でも算盤勘定で帳簿をつけている。
My grandfather still keeps the books using an abacus.
noun
cost-benefit calculation; profit calculation; cold calculation
Figurative use: calculating gains and losses in a detached, often self-interested way. Can carry a negative nuance of being overly mercenary.
彼の行動はいつも算盤勘定だ。
His actions are always based on cold calculation.
友情に算盤勘定を持ち込むな。
Don't bring profit-and-loss thinking into friendship.