Question

6．簡(jiǎn)便運(yùn)算．

0.25×404	1.25×0.7×0.8	6.1×2.6+2.6×3.9
56×1.25	4.75×99+4.75	5.04×1.9-1.8×5.04．

Answer 1

分析 ①把404寫成4×101，根據(jù)乘法結(jié)合律計(jì)算；
②根據(jù)乘法交換律及結(jié)合律計(jì)算；
③根據(jù)乘法分配律進(jìn)行計(jì)算；
④把56寫成7×8，根據(jù)乘法結(jié)合律計(jì)算；
⑤根據(jù)乘法分配律進(jìn)行計(jì)算；
⑥根據(jù)乘法分配律進(jìn)行計(jì)算．

解答 解：①0.25×404             
=0.25×4×101
=1×101
=101

②1.25×0.7×0.8
=1.25×0.8×0.7
=1×0.7
=0.7

③6.1×2.6+2.6×3.9
=2.6×（6.1+3.9）
=2.6×10
=26

④56×1.25              
=7×8×1.25
=7×10
=70

⑤4.75×99+4.75          
=4.75×（99+1）
=4.75×100
=475

⑥5.04×1.9-1.8×5.04
=5.04×（1.9-1.8）
=5.04×0.1
=0.504

點(diǎn)評(píng) 完成本題要注意分析式中數(shù)據(jù)，運(yùn)用合適的簡(jiǎn)便方法計(jì)算．