题目内容
57.5-4.25-15.75 | 125×32 | ×16.31-×2.31 |
99× | 0.76×0.25+×0.24 | ×0.8+×80%+×. |
解:(1)57.5-4.25-15.75,
=57.5-(4.25+15.75),
=57.5-20,
=37.5;
(2)125×32,
=125×(8×4),
=125×8×4,
=1000×4,
=4000;
(3)×16.31-×2.31,
=×(16.31-2.31),
=×14,
=10;
(4)99×,
=(98+1)×,
=98×+1×,
=7+,
=7;
(5)0.76×0.25+×0.24,
=0.76×0.25+0.25×0.24,
=0.25×(0.76+0.24),
=0.25×1,
=0.25;
(6)×0.8+×80%+×,
=×0.8+×0.8+0.8×,
=(++)×0.8,
=1×0.8,
=0.8.
分析:(1)连续减去两个数,就等于减去这两个数的和;
(2)把32拆成8×4,然后再计算即可;
(3)根据乘法分配律进行计算即可;
(4)把99拆成98+1,再根据乘法分配律进行计算即可;
(5)把化成0.25,再根据乘法分配律进行计算即可;
(6)80%化成0.8,化成0.8,再根据乘法分配律进行计算即可.
点评:根据题意,选择合适的运算定律进行简算即可.
=57.5-(4.25+15.75),
=57.5-20,
=37.5;
(2)125×32,
=125×(8×4),
=125×8×4,
=1000×4,
=4000;
(3)×16.31-×2.31,
=×(16.31-2.31),
=×14,
=10;
(4)99×,
=(98+1)×,
=98×+1×,
=7+,
=7;
(5)0.76×0.25+×0.24,
=0.76×0.25+0.25×0.24,
=0.25×(0.76+0.24),
=0.25×1,
=0.25;
(6)×0.8+×80%+×,
=×0.8+×0.8+0.8×,
=(++)×0.8,
=1×0.8,
=0.8.
分析:(1)连续减去两个数,就等于减去这两个数的和;
(2)把32拆成8×4,然后再计算即可;
(3)根据乘法分配律进行计算即可;
(4)把99拆成98+1,再根据乘法分配律进行计算即可;
(5)把化成0.25,再根据乘法分配律进行计算即可;
(6)80%化成0.8,化成0.8,再根据乘法分配律进行计算即可.
点评:根据题意,选择合适的运算定律进行简算即可.
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