下面各题,能简算的要用简便方法计算.2.9+0.46+7.1+0.5430÷2.5+1.6×2.50.4×(25+2.5)4.97×[2.46÷(5.58-5.28)].
(1)2.9+0.46+7.1+0.54, =(2.9+7.1)+(0.46+0.56), =10+1, =11; (2)30÷2.5+1.6×2.5, =12+4, =16; (3)0.4×(25+2.5), =25×0.4+2.5×0.4, =10+1, =11; (4)4.97×[2.46÷(5.58-5.28)], =4.97×[2.46÷0.3], =4.97×8.2, =40.754. |
下面各题,能简算的要用简便方法计算.2.9+0.46+7.1+0.5430÷2.5+1.6×...
(1)2.9+0.46+7.1+0.54,=(2.9+7.1)+(0.46+0.56),=10+1,=11;(2)30÷2.5+1.6×2.5,=12+4,=16;(3)0.4×(25+2.5),=25×0.4+2.5×0.4,=10+1,=11;(4)4.97×[2.46÷(5.58-5.28)],=4.97×[2.46÷0.3],=4.97×8.2,=40...
下面各题,能简算的要用简便方法计算. 7.9+0.46-0.9+0.5430÷2.5+1.6×...
答案 解析 ①7.9+0.46-0.9+0.54利用加法的交换律和结合律变成(7.9-0.9)+(0.46+0.54);②30÷2.5+1.6×2.5按四则运算的运算顺序,30÷2.5和1.6×2.5同时计算,再算加;③1.25×19.4×0.8利用乘法的交换律和结合律变成(1.25×0.8)×19.4计算简便;④4.3×10.2...