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2.5×56+4.5×65简算

题目详情
2.5×56+4.5×65 简算
▼优质解答
答案和解析
(2.5+4.5)×56×65肯定是错误的.
2.5×56+4.5×65
=2.5×56+45×6.5
= 2.5×56+44×6.5+6.5
=2.5×56+44×(2.5+4)+6.5
=2.5×56+44×2.5+44×4+6.5
=2.5×(56+44)+44×4+6.5
=2.5×100+44×4+6.5
=250+176+6.5
=426+6.5
=432.5
或者说:
=2.5×4×14+292.5
=10×14+292.5
=140+292.5
=432.5
4.5×65参照尾同首合十的口算方法.