Question

求几道简便运算题 五年级寒假作业的！！急急急

必须要简便运算！~
2.5×1.25×32 （10＋0.1＋0.01）×39 6.19×2.05＋79.5×0.619

0.86＋9.9×8.6

Answer 1

2.5×1.25×32
=2.5×1.25×4×8
=2.54×8×1.25
=10×10
=100
（10＋0.1＋0.01）×39
=10×39+0.1×39+0.01×39
=390+3.9+0.39
=394.29
6.19×2.05＋79.5×0.619
=6.19×2.05＋7.95×6.19
=6.19×(2.05+7.95)
=61.9
0.86＋9.9×8.6
=8.6×0.1+9.9×8.6
=8.6×(0.1+9.9)
=86

Answer 2

2.5×1.25×32 （10＋0.1＋0.01）×39 6.19×2.05＋79.5×0.619
＝2.5*1.25*（4*8） ＝10*39+0.1*39+0.01*39 ＝6.19*20.5+79.5*6.19
＝6.19*（20.5+79.5）
＝（2.5*4）*（1.25*8）

0.86＋9.9×8.6
＝0.86+99*0.86
＝（99+1）*0.86

希望能帮到你，也希望你能选我。谢谢！

Answer 3

2.5×1.25×32
=2.5×1.25×4×8
=（2.5×4）×（1.25×8）
=10×10
=100
（10+0.1+0.01）×39
=10×39+0.1×39+0.01×39
=390+3.9+0.39
=394.29
6.19×2.05+79.5×0.619
=6.19×2.05+7.95×6.19
=6.19×（2.05+7.95）
=6.19×10
=61.9
0.86+9.9×8.6
=8.6×0.1+9.9×8.6
=8.6×（0.1+9.9）
=8.6×10
=86

Answer 4

(2.5*4)*(1.25*8)=10*10=100
39*10+39*0.1+39*0.01=390+3.9+0.39=394.29
0.619*10*2.05+79.5*0.619=0.619(20.5+79.5)=61.9
8.6(0.1+9.9)=86

Answer 5

① =（2.5×2）＋（1.25×30） ③ =6.19×（2.05＋7.95）
=5＋24 =6.19×10
=29 =61.9