问题
解答题
用简便方法计算下列各题. ①2.84×
②38×
③0.125×32×2.5 ④72×(
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答案
①2.84×
+4.16÷3 7
,7 3
=(2.84+4.16)×
,3 7
=7×
,3 7
=3;
②38×
+17×0.25+45×25%,1 4
=(38+17+45)×0.25,
=100×0.25,
=25;
③0.125×32×2.5,
=(0.125×8)×(4×2.5),
=1×10,
=10;
④72×(
-5 9
)+10,5 12
=72×
-72×5 9
+10,5 12
=40-30+10,
=20.