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简介:
一、乘法交换律
0.25×8.5×4
=0.25×4×8.5
=1×8.5
=8.5 12.5×0.96×0.8
=12.5×0.8×0.96
=10×0.96
=9.6 0.5×0.34×0.6
=0.5×0.6×0.34
=0.3×0.34
=0.102
二、乘法结合律
4.36×12.5×8
=4.36×(12.5×8)
=4.36×100
=436 0.95×0.25×4
=0.95×(0.25×4)
=0.95×1
=0.95 0.75×50×0.4
=0.75×(50×0.4)
=0.75×20
=15
三、添加因数“1”
56.5×99+56.5
=56.5×99+56.5×1
=56.5×(99+1)
=56.5×100
=5650 9.7×99+9.7
=9.7×99+9.7×1
=9.7×(99+1)
=9.7×100
=970 4.2×99+4.2
=4.2×99+4.2×1
=4.2×(99+1)
=4.2×100
=420
四、乘法分配律
(1.25-0.125)×8
=1.25×8-0.125×8
=10-1
=9 (正用) (1.25+2.5)×0.8
=1.25×0.8+2.5×0.8
=1+2
=3 (正用) 3.72×3.5+6.28×3.5
=3.5×(3.72+6.28)
=3.5×10
=35 (逆用)