haihongyuan.com

# 五年级上九单元小数乘法简便计算--山西路姚光博

2.5 ×0.73 × 4 =2.5 × 4 × 0.73 乘法交换律

=10× 0.73 =7.3

0.96 ×12.5 × 0.8 乘法结 =0.96× （12.5 ×0.8 ） 合律

=0.96× 10 =9.6

7.6 ×0.8 +0.2× 7.6 =7.6× （ 0.8 +0.2 ） 乘法分配律

=7.6× 1 =7.6

（2.4－0.16）× 0.5 =2.4× 0.5 －0.16×0.5

=1.2－ 0.08 =1.12

1、加减法拆分
10.2=( 10 )+( 0.2 ) 9.9=( 10 )－( 0.1 )

2、乘法拆分
3.5×22=3.5× 2×11

0.15 ×36
102×32

0.15×36
= 0.15×4×9 = 0.6×9 = 5.4

102×32
= (100+2)×32 = 100×32+2×32 = 3200+64 = 3264

0.85 ×99 0.85 × 99 + 0.85

0.85 × 99 + 0.85
=0.85 × 99 + 0.85 ×1 =0.85×（99+1） =0.85×100 =85

28.6 ×101 － 28.6 =28.6 ×101 － 28.6×1 =28.6×（101-1） =28.6×100 =2860

7.6×9.8+0.2×7.6 = 7.6×(0.8+0.2) = 7.6×1 = 7.6 0.25×32×1.25 =0.25×4×8×1.25 = (0.25×4)×(8 ×1.25) = 1×10 = 10 0.25×28 = 0.25×4×7 = 1×7 =7

0.85×99 = 0.85×(100-1) = 0.85×100-0.85×1 = 85-0.85 = 84.15

0.85×99+0.85 = 0.85×99+0.85×1 = 0.85×(99+1) = 0.85×100 =85

76×0.08+0.2×7.6 = 7.6×0.8+0.2×7.6 = 7.6×(0.8+0.2) = 7.6×1 = 7.6 1.28×8.6+1.44×4.3 = 1.28×8.6+0.72×2×4.3 = 1.28×8.6+0.72×8.6 = (1.28+0.72) ×8.6 = 2×8.6 =17.2

2.4×1.02-0.048 = 2.4×1.02-2.4×0.02 = 2.4×(1.02-0.02) = 2.4×1 = 2.4 12×0.86+2.5×0.86+0.43 = 24×0.43+5×0.43+1×0.43 = (24+5+1) ×0.43 = 30×0.43 =12.9

——牛顿

1. 乘法运算律的整理回顾 2.小数乘法的简便计算题型汇总 3.小数乘法的简便计算技巧总结 4.小结

1.25 ×7.8×（ 8 ）

8.6×1.28+ 0.72 ×（8.6）