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简介：
常见敏感算式：
125×8=1000 25×4=100 5×2=10 5×4=20 5×6=30 5×8=40
数字拆分：
24=4×6 48=6×8 32=4×8 36=4×9
48=4×12 24=20+4 48=40+8 97=100-3
98=100-2 99=100-1 101=100+1 102=100+2
一、乘法交换律
(1)2.5×9×4
=2.5×4×9
=10×9
=90 (2)1.5×7×6
=1.5×6×7
=9×7
=63 (3)0.8×1.4×12.5
=0.8×12.5×1.4
=10×1.4
=14
(4)0.5×0.34×6
=0.5 × 6 ×0.34
=3×0.34
=1.36 (5)0.25×0.46×40
=0.25 × 40 × 0.46
=10×0.46
=4.6 (6)0.8×0.46×0.5
=0.8 × 0.5 ×0.46
=0.4×0.46
=0.184
二、乘法结合律
(1)4.31×1.25×0.8
=4.31×1
=4.31 (2)0.79×5×2
=0.79×10
=7.9 (3)0.16×2.5×400
=0.16×1000
=160
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