用简便方法计算下面各题. (1)2.9×0.45+0.29×4.2+0.029×13 (2)3.84×9.6+0.96×61.6.

问题描述:

用简便方法计算下面各题.
(1)2.9×0.45+0.29×4.2+0.029×13
(2)3.84×9.6+0.96×61.6.


(1)2.9×0.45+0.29×4.2+0.029×13,
=2.9×0.45+2.9×0.42+2.9×0.13,
=2.9×(0.45+0.42+0.13),
=2.9×1,
=2.9;
(2)3.84×9.6+0.96×61.6,
=3.84×9.6+9.6×6.16,
=(3.84+6.16)×9.6,
=10×9.6,
=96.