1125-997998+1246+9989(8700+870+87)÷87
125×8.81.3+4.25+3.7+3.7517.15-(3.5-2.85)
3.4×99+3.44.8×1.010.4×(2.5÷73)
(1.6+1.6+1.6+1.6)×25(+-)÷
12.3-2.45-5.7-4.552+0.125×0.25×64
64.2×87+0.642×130078×36+7.8×741-717+8
0.125×+0.52.42+4.58-43
25÷1004.25-3-(2-1)
(1)1.25*17.6+36.1/0.8+2.36*12.5
1.25*17.6+36.1/0.8+2.36*12.5
=(5/4)*17.6+36.1*(5/4)+23.6*(50/4)
=176/8+361/8+236/8
=773/8=96.625
(2)7.5*2.3+1.9*2.5
7.5*2.3+1.9*2.5
=7.5*(1.9+0.4)+1.9*2.5
=(7.5+2.5)*1.9+7.5*0.4
=19+3=22
(3)2004/2003*2005
2004/2003*2005
=(2004/2003)*(2003+2)
=2004+4008/2003
(4)276*543-267/276+543*275
276*543-267/276+543*275
=543*(276+275)-267/276
=543*551-267/276
(5)17/51+(68/1+51/2)*17
17/51+(68/1+51/2)*17
后面的做不下去了,好像有一些没有简便方法,不知道你题目有没有抄错,你的68/1中的68是分子还是分母呀?应该是分母都对
(6)(3.25-0.8*8/5)/(6又4/1-3.5)
是6又1分之4吗?应该是6又4分之1吧
1)五十二又二十五分之十一×79.45+159×47.56+七十九又二十分之十一×52.44
=52.44×79.45+159×47.56+79.55×52.44
=52.44×(79.45+79.55)+159×47.56
=52.44×159+159×47.56
=159×(52.44+47.56)
=159×100
=15900
3)2002+2001-2000-1999+1998+1997-1996-1995+……+2+1
=(2002-2000)+(2001-1999)+(1998-1996)+(1997-1995)+……+(6-4)+(5-3)+2+1
=2+2+2+2+……+2+2(从3-2002共2000个数,所以有1000个2)+2+1
=1000×2+2+1
=2003
4,5两题均用到一个转换式1/(A×B)=1/(B-A)×(1/A-1/B)
如1/15=1/(3×5)=1/(5-3)×(1/3-1/5)=1/2×(2/15)=1/15可验证一下
4)(1×2分之一)+(2×3分之一)+(3×4分之一)+……+(10×11分之一)
=1/(1×2)+1/(2×3)+1/(3×4)+……+1/(10×11)
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/10-1/11)
=1-1/11
=10/11
5)三分之一+十五分之一+三十五分之一+六十三分之一+九十九分之一
=1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)
=1/2×(1-1/3)+1/2×(1/3-1/5)+1/2×(1/5-1/7)+1/2×(1/7-1/9)+1/2×(1/9-1/11)
=1/2×(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)
=1/2×(1-1/11)
=1/2×10/11
=5/11
6)一又二分之一-六分之五+十二分之七-二十分之九+三十分之十一-四十二分之十三+五十六分之十五
(根据提示,1又1/2=1+1/2,+1/2+1/3=5/6……)
=(1+1/2)-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)
=1+1/2-1/2-1/3+1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8
=1+1/8
=9/8
1.3/7×49/9-4/3
2.8/9×15/36+1/27
3.12×5/6–2/9×3
4.8×5/4+1/4
5.6÷3/8–3/8÷6
6.4/7×5/9+3/7×5/9
7.5/2-(3/2+4/5)
8.7/8+(1/8+1/9)
9.9×5/6+5/6
10.3/4×8/9-1/3
11.7×5/49+3/14
12.6×(1/2+2/3)
13.8×4/5+8×11/5
14.31×5/6–5/6
15.9/7-(2/7–10/21)
16.5/9×18–14×2/7
17.4/5×25/16+2/3×3/4
18.14×8/7–5/6×12/15
19.17/32–3/4×9/24
20.3×2/9+1/3
21.5/7×3/25+3/7
22.3/14××2/3+1/6
23.1/5×2/3+5/6
24.9/22+1/11÷1/2
25.5/3×11/5+4/3