题目内容
7.脱式计算,能简算的要简算.8.37-(2.5+6.837) | 12.5×32×2.5 | $\frac{4}{5}$÷[($\frac{3}{5}$+$\frac{1}{2}$)×2] |
77×$\frac{4}{5}$+23×$\frac{4}{5}$ | (1-0.8×$\frac{3}{4}$)÷$\frac{4}{5}$ | ($\frac{1}{3}$+$\frac{1}{6}$-$\frac{1}{9}$)×54 |
分析 (1)先算小括号里面的加法,再算括号外的减法;
(2)先把32分解8×4,再根据乘法结合律简算;
(3)先算小括号里面的加法,再算中括号里面的乘法,最后算括号外的除法;
(4)根据乘法分配律简算;
(5)先算小括号里面的乘法,再算小括号里面的减法,然后算括号外的除法;
(6)运用乘法分配律简算.
解答 解:(1)8.37-(2.5+6.837)
=8.37-9.337
=-0.967
(2)12.5×32×2.5
=12.5×(8×4)×2.5
=(12.5×8)×(4×2.5)
=100×10
=1000
(3)$\frac{4}{5}$÷[($\frac{3}{5}$+$\frac{1}{2}$)×2]
=$\frac{4}{5}$÷[$\frac{11}{10}$×2]
=$\frac{4}{5}$÷$\frac{11}{5}$
=$\frac{4}{11}$
(4)77×$\frac{4}{5}$+23×$\frac{4}{5}$
=(77+23)×$\frac{4}{5}$
=100×$\frac{4}{5}$
=80
(5)(1-0.8×$\frac{3}{4}$)÷$\frac{4}{5}$
=(1-0.6)÷$\frac{4}{5}$
=0.4÷$\frac{4}{5}$
=0.5
(6)($\frac{1}{3}$+$\frac{1}{6}$-$\frac{1}{9}$)×54
=$\frac{1}{3}$×54+$\frac{1}{6}$×54-$\frac{1}{9}$×54
=18+9-6
=21
点评 本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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