39×39/40用简便计算？

Question

如题所述

Answer 1

39×39/40
=（40-1）×39/40
=40×39/40-1×39/40
=39-39/40
=38又1/40本回答被网友采纳

Answer 2

39×39/40
=（40-1）×39/40
=40×39/40-39/40
=39-39/40
=38又1/40

Answer 3

解：39x39/40
=39x(1-1/40)
=39-39/40
=38又1/40