文档介绍：小数乘法的简便运算
苏教版五年级上册实验教科书
比一比
看谁算得快
×100
24+
15-
×
×8
×4
×5
×
= 32
=
=
=
= 10
= 10
=
=
比一比
看谁算得巧
(23×4)×15
25×73×4
102×32
= 25×4×73
= 100×73
= 7300
= 23×(4×15)
= 23×60
= 1380
= (100+2)×32
= 100×32+2×32
= 3200+64
= 3264
分组计算
男生组女生组
× ×
(×)× ×(×)
(+) × ×+×
=
=
=
观察每组的两个算式有什么不同? 你能得出什么结论?
结论:
整数的运算律同样适用于小数。
练一练
×+×
×36
×99
76×+×
×32×
×99+
= ×(+)
= ×1
=
= ×4×9
= 1×9
= 9
= ×(100-1)
= ×100-×1
= 85-
=
= ×+×
= ×(+)
= ×1
=
=×4×8×
= (×4)×(8 ×)
= 1×10
= 10
= ×99+×1
= ×(99+1)
= ×100
=85
练一练
××4
×
×+×
×(+++)
×-
×+×
×+×-
= ×4×
= 1×
=
= ×-×
= ×(-)
=