考點(diǎn):運(yùn)算定律與簡便運(yùn)算
專題:運(yùn)算定律及簡算
分析:(1)可將12.6變?yōu)?2.5+0.1后,根據(jù)乘法分配律計(jì)算.
(2)可將99.6變?yōu)?00-0.4后,根據(jù)乘法分配律計(jì)算.
(3)可將100.1變?yōu)?00+0.1后,根據(jù)乘法分配律計(jì)算.
(4)可將9.3×17變?yōu)?3×1.7后,根據(jù)乘法分配律計(jì)算.
(5)可將8.8變?yōu)?+0.8后,根據(jù)乘法分配律計(jì)算.
(6)可根據(jù)乘法分配律計(jì)算.
解答:
解:(1)12.6×0.8
=(12.5+0.1)×0.8
=12.5×0.8+0.1×0.8
=10+0.08
=10.08;
(2)99.6×2.5
=(100-0.4)×2.5
=100×2.5-0.4×2.5
=250-1
=248;
(3)8.7×100.1
=8.7×(100+0.1)
=8.7×100+8.7×0.1
=870+0.87
=870.87;
(4)9.3×17+93×8.3
=93×1.7+93×8.3
=93×(1.7+8.3 )
=93×10
=930;
(5)12.5×8.8
=12.5×(8+0.8)
=12.5×8+12.5×0.8
=100+10
=110;
(6)401×0.25-0.25
=(401-1)×0.25
=400×0.25
=100.
點(diǎn)評:本題考查考查了學(xué)生靈活運(yùn)用乘法分配律對算式進(jìn)行簡便計(jì)算的能力.