用简便方法计算下面各题. 3.8×6.7+3.3×3.8 1.28×0.29-0.29×0.28 101×4.8 56×12.5×2.
问题描述:
用简便方法计算下面各题.
3.8×6.7+3.3×3.8
1.28×0.29-0.29×0.28
101×4.8
56×12.5×2.
答
(1)3.8×6.7+3.3×3.8
=(6.7+3.3)×3.8
=10×3.8
=38;
(2)1.28×0.29-0.29×0.28
=(1.28-0.28)×0.29
=1×0.29
=0.29;
(3)101×4.8
=(100+1)×4.8
=100×4.8+1×4.8
=480+4.8
=484.8.
(4)56×12.5×2
=7×(8×12.5)×2
=7×100×2
=1400.