Question

5.6x2.9+42x0.28的简便方法？

Answer 1

本题运用的知识点:（1）两个因数相乘，一个扩大n倍，另一个因数缩小n倍，积不变。（2）乘法分配律逆运算。解:5.6×2.9+42×0.28=5.6×29+（42÷20）×（0.28×20）=5.6×2.9+2.1×5.6=5.6×（2.9+2.1）=5.6×5=28

Answer 2

5.6x2.9+42x0.28的简便方法=2.8x2x2.9+4.2x2.8=10x2.8=28

Answer 3

5.6x2.9+42x0.28的简便方法？
用乘法分配律计算即可
5.6x2.9+42x0.28
=2.8x2x2.9+4.2x2.8
=2.8x（5.8+4.2）
=2.8x10
=28

Answer 4

将后面的42×0.28换算成2.1×5.6，那么：=5.6×2.9+2.1×5.6
=5.6×（2.9+2.1）
=5.6×5
=28

Answer 5

5.6×2.9+42×0.28
＝5.6×2.9+4.2×2.8
＝（5.6+4.2)×2.8+5.6×0.1
＝9.8×2.8+0.56
＝10×2.8-2.8×0.2+0.56
＝28-0.56+0.56
＝28