简算.(1)2.4×0.19+0.24×8.1(2)18.8×10.1-1.88(3)0.79×0.46+7.9×0.053+0.0079.
问题描述:
简算.
(1)2.4×0.19+0.24×8.1
(2)18.8×10.1-1.88
(3)0.79×0.46+7.9×0.053+0.0079.
答
(1)2.4×0.19+0.24×8.1,
=2.4×0.19+2.4×0.81,
=2.4×(0.19+0.81),
=2.4×1,
=2.4;
(2)18.8×10.1-1.88,
=1.88×101-1.88,
=1.88×101-1.88,
=1.88×(101-1),
=1.88×100,
=188;
(3)0.79×0.46+7.9×0.053+0.0079,
=0.0079×46+0.0079×53+0.0079,
=0.0079×(46+53+1),
=0.0079×100,
=0.79.
答案解析:(1)把原式变为2.4×0.19+2.4×0.81,运用乘法分配律简算;
(2)把原式变为1.88×101-1.88,运用乘法分配律简算;
(3)把原式变为0.0079×46+0.0079×53+0.0079,运用乘法分配律简算.
考试点:小数四则混合运算.
知识点:通过数字变形,运用乘法分配律简算.