题目内容
计算下面各题.(带﹡的用简便方法计算)
300-12×13 | 700÷(38+32) | 514-79+21 | ﹡82+(555+18) | ﹡28×25 | ﹡720÷16÷5. |
分析:(1)先算乘法,再算减法;
(2)先算小括号里面的加法,再算除法;
(3)先算减法,再算加法;
(4)根据加法交换律和结合律进行简算;
(5)把28拆成4×7,然后再根据乘法交换律和结合律进行简算;
(6)720连续除以16与5,等于除以16与5的积.
(2)先算小括号里面的加法,再算除法;
(3)先算减法,再算加法;
(4)根据加法交换律和结合律进行简算;
(5)把28拆成4×7,然后再根据乘法交换律和结合律进行简算;
(6)720连续除以16与5,等于除以16与5的积.
解答:解:(1)300-12×13,
=300-156,
=144;
(2)700÷(38+32),
=700÷70,
=10;
(3)514-79+21,
=435+21,
=456;
(4)82+(555+18),
=(82+18)+555,
=100+555,
=655;
(5)28×25,
=(4×7)×25,
=(4×25)×7,
=100×7,
=700;
(6)720÷16÷5,
=720÷(16×5),
=720÷80,
=9.
=300-156,
=144;
(2)700÷(38+32),
=700÷70,
=10;
(3)514-79+21,
=435+21,
=456;
(4)82+(555+18),
=(82+18)+555,
=100+555,
=655;
(5)28×25,
=(4×7)×25,
=(4×25)×7,
=100×7,
=700;
(6)720÷16÷5,
=720÷(16×5),
=720÷80,
=9.
点评:根据题意,找清运算顺序,然后再进一步计算即可,能简算的要简算.
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