用简便方法计算下面各题.(1)12.5×2.5×3.2(2)5.6÷0.32(3)100.1×23(4)89-12+58+12(5)1-512-712(6)718-(518-89)-五年级数学
题文
用简便方法计算下面各题. (1)12.5×2.5×3.2 (2)5.6÷0.32 (3)100.1×23 (4)
(5)1-
(6)
|
答案
(1)12.5×2.5×3.2 =12.5×2.5×(0.4×8), =(12.5×8)×(2.5×0.4), =100×1, =100; (2)5.6÷0.32 =5.6÷(0.8×0.4), =5.6÷0.8÷0.4, =7÷0.4, =17.5; (3)100.1×23 =(100+0.1)×23, =100×23+0.1×23, =2300+2.3, =2302.3; (4)
=(
=
=
(5)1-
=1-(
=1-1, =0; (6)
= |