2.5+7.5×(3.64-1.24) 简便计算

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2.5+7.5×(3.64-1.24) 简便计算
2.5+7.5×(3.64-1.24) 简便计算

2.5+7.5×(3.64-1.24) 简便计算
2.5+7.5×(3.64-1.24)
=2.5+7.5×2.5
=2.5×(1+7.5)
=2.5×(8+0.5)
=2.5 ×8+2.5×0.5
=20+1.25
=21.25

2.5+7.5×(3.64-1.24)
=2.5+7.5×2.4
=2.5+2.5×3×2.4
=2.5+2.5×7.2
=2.5×(1+7.2)
=2.5×8.2
=2.5×8+2.5×0.2
=20+0.5
=20.5