Question

12．我能用喜歡的方法計(jì)算下面各題．
①1.25×4.78×0.8
②6.1×3.6+3.6×3.9
③102×2.5
④9.07-22.78÷3.4．

Answer 1

分析 ①用乘法交換律和結(jié)合律計(jì)算．把1.25和0.8結(jié)合算出得數(shù)是1，再用1乘4.78即可．
②用乘法分配律計(jì)算即可．
③把102變成100+2，再用乘法分配律計(jì)算即可．
④先算除法再算減法．

解答 解：①1.25×4.78×0.8
=（1.25×0.8）×4.78
=1×4.78
=4.78

②6.1×3.6+3.6×3.9
=（6.1+3.9）×3.6
=10×3.6
=36

③102×2.5
=（100+2）×2.5
=100×2.5+2×2.5
=250+5
=255

④9.07-22.78÷3.4
=9.07-6.7
=2.37

點(diǎn)評(píng) 此題考查了學(xué)生對(duì)小數(shù)四則混合運(yùn)算題的計(jì)算能力，以及靈活巧算的能力．