题目内容
20.下面各题怎样算简便就怎样算.| 1375-450÷18×25 | (9.6×$\frac{5}{6}$-7.2)÷$\frac{9}{4}$ | 2.84×$\frac{3}{7}$+4.16÷$\frac{7}{3}$ |
| 0.25×1.25×32×$\frac{1}{10}$ | 2.25×$\frac{3}{5}$+2.75÷1$\frac{2}{3}$+60% | $\frac{1}{50}$+(2-0.47 )×$\frac{3}{20}$ |
分析 (1)先算除法,再算乘法,最后算减法;
(2)先算小括号里面的乘法,再算小括号里面的减法,最后算括号外的除法;
(3)(5)先把除法变成乘法,再运用乘法分配律简算;
(4)先把32分解成4×8,再根据乘法交换律和结合律简算;
(6)先算小括号里面的减法,再算括号外的乘法,最后算括号外加法.
解答 解:(1)1375-450÷18×25
=1375-25×25
=1375-625
=750
(2)(9.6×$\frac{5}{6}$-7.2)÷$\frac{9}{4}$
=(8-7.2)÷$\frac{9}{4}$
=0.8÷$\frac{9}{4}$
=$\frac{16}{45}$
(3)2.84×$\frac{3}{7}$+4.16÷$\frac{7}{3}$
=2.84×$\frac{3}{7}$+4.16×$\frac{3}{7}$
=(2.84+4.16)×$\frac{3}{7}$
=7×$\frac{3}{7}$
=3
(4)0.25×1.25×32×$\frac{1}{10}$
=0.25×1.25×(4×8)×0.1
=(0.25×4)×(1.25×8)×0.1
=1×10×0.1
=1
(5)2.25×$\frac{3}{5}$+2.75÷1$\frac{2}{3}$+60%
=2.25×$\frac{3}{5}$+2.75×$\frac{3}{5}$+60%
=(2.25+2.75+1)×$\frac{3}{5}$
=6×$\frac{3}{5}$
=3.6
(6)$\frac{1}{50}$+(2-0.47 )×$\frac{3}{20}$
=$\frac{1}{50}$+1.53×$\frac{3}{20}$
=0.02+0.2295
=0.2495
点评 本题考查了四则混合运算,计算时先理清楚运算顺序,根据运算顺序逐步求解即可.
| A. | 81×100+10 | B. | 80×110+110 | C. | 81×100+81×10 |