Question

56×9.9+5.6×0.2-5.6的简便算法是什么？

Answer 1

这道题的简便算法是逆用乘法分配律。
56×9.9+5.6×0.2-5.6
=56×(10-0.1)-5.6×(1-0.2)
=56×10-56×0.1-5.6×0.8
=560-(5.6×1+5.6×0.8)
=560-5.6×(1+0.8)
=560-5.6×1.8
=560-5.6×(2-0.2)
=560-5.6×2+5.6×02
=560-11.2+1.12
=548.8+1.12
=549.92

Answer 2

我感觉题干应该错了，应该是算56×9.9+5.6×2-5.6
56×9.9+5.6×2-5.6=5.6*(99+2-1)=5.6*100=560

Answer 3

56×9.9+5.6×0.2-5.6
＝5.6×99+5.6×0.2-5.6
＝5.6×（99+0.2-1）
＝5.6×98.2
＝5.6×（100-1-0.8）
＝5.6×100-5.6-5.6×0.8
＝560-5.6-4.48
＝560-（5.6+4.48）
＝560-10.08
＝549.92