Question

9．脫式計(jì)算，能簡(jiǎn)算的要簡(jiǎn)算．

0.125×32	0.78×101	69.6÷3.2÷2.5
60.8-36÷7.5	3.09×3.9÷2.6	3.072÷6.4+49.7

Answer 1

分析 ①先把32分解成8×4，再運(yùn)用乘法結(jié)合律計(jì)算；
②運(yùn)用乘法分配律可簡(jiǎn)便計(jì)算；
③⑤根據(jù)運(yùn)算順序從左到右依次計(jì)算；
④先算除法，再算減法；
⑥先算除法，再算加法．

解答 解：
①0.125×32
=0.125×8×4
=1×4
=4

②0.78×101
=0.78×（10+1）
=0.78×100+0.78×1
=78+0.78
=78.78

③69.6÷3.2÷2.5
=21.75÷2.5
=8.7

④60.8-36÷7.5
=60.8-4.8
=56

⑤3.09×3.9÷2.6
=12.051÷2.6
=4.635

⑥3.072÷6.4+49.7
=0.48+49.7
=50.18

點(diǎn)評(píng) 此題考查小數(shù)四則混合運(yùn)算順序，靈活運(yùn)用運(yùn)算定律簡(jiǎn)算．