灵活计算下面各题.?????????????
5.02-1.37-2.63??????
1.25×2.5×32?????????
×(+)+0.8.
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解:(1)5.02-1.37-2.63,
=5.02-(1.37+2.63),
=5.02-4,
=1.02;
(2)1.25×2.5×32,
=1.25×2.5×4×8,
=(1.25×8)×(2.5×4),
=10×10,
=100;
(3)×(+)+0.8,
=×+×+0.8,
=2++,
=2+(+),
=2+2,
=4.
解析分析:(1)根据连续减去两个数等于减去这两个数的和简算;
(2)把32分解成4×8,再运用乘法结合律简算;
(3)先运用乘法分配律简算,再运用加法结合律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.