题目内容
灵活计算下面各题.
(1)7.16-2.09-3.01
(2)12.5×(7.3-3.7)×0.8
(3)5.46×6.5+1.85
(4)(6+9.728÷3.2)×2.5.
(1)7.16-2.09-3.01
(2)12.5×(7.3-3.7)×0.8
(3)5.46×6.5+1.85
(4)(6+9.728÷3.2)×2.5.
分析:(1)根据一个数连续减去两个数,可以用这个数减去这两个数的和;
(2)先计算出括号内的减法,再运用乘法交换律结合律进行计算.
(3)先算乘法,再算加法;根据四则混合运算的顺序计算;
(4)先计算出括号内的除法,再运用乘法结合律简算;
(2)先计算出括号内的减法,再运用乘法交换律结合律进行计算.
(3)先算乘法,再算加法;根据四则混合运算的顺序计算;
(4)先计算出括号内的除法,再运用乘法结合律简算;
解答:解:(1)7.16-2.09-3.01
=7.16-(2.09+3.01)
=7.16-5.1
=2.06;
(2)12.5×(7.3-3.7)×0.8
=12.5×3.6×0.8
=(12.5×0.8)×3.6
=10×3.6
=36;
(3)5.46×6.5+1.85
=35.49+1.85
=37.34;
(4)(6+9.728÷3.2)×2.5.
=(6+3.04)×2.5
=6×2.5+3.04×2.5
=15+7.6
=22.6.
=7.16-(2.09+3.01)
=7.16-5.1
=2.06;
(2)12.5×(7.3-3.7)×0.8
=12.5×3.6×0.8
=(12.5×0.8)×3.6
=10×3.6
=36;
(3)5.46×6.5+1.85
=35.49+1.85
=37.34;
(4)(6+9.728÷3.2)×2.5.
=(6+3.04)×2.5
=6×2.5+3.04×2.5
=15+7.6
=22.6.
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.
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