9.9*2.5的简便-搜答案-智慧作业帮

(10-0.1)*2.5=10*2.5-0.1*2.5=25-0.25=24.75

原式=（10-0.1）×12.8+3.6=128-1.28+3.6=130.32

0.79*10-0.79*0.1

9.9+99.9+999.9+1＝10－0.1＋100－0.1＋1000－0.1＋1＝1111－0.3＝1110.7

=(1-0.1)*(10-0.1)*(100-0.1)=1*10*100-1*100-0.1*100+0.1^2*100-10*0.1+1*0.1+0.1^2-0.1^3=890.109技巧就是学会“

1.36×9.9+1.36×0.1=1.36×10=13.6

21.6*9.9=21.6*（10-0.1）=216-2.16=213.84

3.58×9.9+0.058=3×9.9+0.58×9.9+0.58×0.1=3×10-3×0.1+0.58×（9.9+0.1）=30-0.3+5.8=35.5

9.9X9.81=(10-0.1)X9.81=10X9.81-0.1x9.81=98.1-0.981=97.119

题目是不是2.3*9.9+0.23的简便计算=2.3*9.9+2.3*0.1=2.3*(9.9+0.1)=23

0.78*9.9的简便算法

=0.78*（10-0.1）=0.78*10-0.78*0.1=7.8-0.078=7.722

4.25÷2.5×9.9+0.17=1.7×9.9+0.17=1.7×9.9+0.1×1.7=1.7×（9.9+0.1）=1.7×10=17

2.64*9.9+0.264=0.264*99+0.264*1=(99+1)*0.264=0.264*100=26.4

3.5×9.9＋3.5=3.5*（10-0.1）+3.5=3.5*10-3.5*0.1+3.5=35+3.5-0.35=38.5-0.35=38.15

再答：给个釆纳，新年快乐再问：祝你新年快乐

0.9+9.9+99.9=1-0.1+10-0.1+100-0.1=1+10+100-3×0.1=111-0.3=110.7

9.9×99=9.9×100-9.9=990-9.9=980.1

8.7×9.9的简便计算

8.7X9.9=8.7X(10-0.1)=8.7X10-8.7X0.1=87-0.87=86.13