用简便方法计算![]() |
| 解:(1)37×20.2, =37×(20+0.2), =37×20+37×0.2, =740+7.4, =747.4; (2)1.25×3.2×2.5, =1.25×8×0.4×2.5, =(1.25×8)×(0.4×2.5), =10×1, =10; (3)20÷0.4÷2.5, =20÷(0.4×2.5), =20÷1, =20 |
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a.缩小为原来的[ ]
[ ]
a.4.5÷l.5
,那么积[ ]
a.扩大为原来的5倍
,另一个因数不变,积[ ]
a.扩大为原来的100倍