2.(1+1/2)*(1-1/2)*1+1/3)*(1-1/3)*........*(1+1/9)*(1-1/9)
3.1/2 * 3+1/3 * 4+...+1/19乘以20。
4.1/27+505/2727+131313/272727
5.100-98+96-94+....+4-2
1.(1/69+2/71)乘以23+25除以71。
=1/69*23+2/71*23+25/71
=1/3+(46/71+25/71)
=1/3+1
=4/3
2.(1+1/2)次(1-1/2)次(1+1/3)次(1-1/3)
=3/2*1/2*4/3*2/3...*10/9*8/9
=1/2*10/9
=5/9
3.1/2乘以3+1/3乘以4+...+1/19乘以20
=1/2-1/3+1/3-1/4+...+1/19-1/20
=1/2-1/20
=9/20
4.1/27+505/2727+131313/272727
=1/27+5*101/(27*101)+13*10101/(27*10101)
=1/27+5/27+13/27
=19/27
5.100-98+96-94+....+4-2
=(100-98)+(96-94)+...(4-2)
=2+2+...+2(***有25)
=2*25
=50
10-2.65=
0.9×0.08=
528-349=
6+14.4=
24÷0.04=
12.34-2.3=
0÷3.8=
0.77+0.33=
7÷1.4=
67.5+0.25=
7.2÷8×4=
5-1.4-1.6=
400÷125÷8=
1.9×4×0.5=
80×0.125=
2×5-6+2=
3.2×7÷3.2×7=
4 +3.2+5 +6.8 25×(8×0.4)×1.25 7
1125-997 998+1246+9989 (8700+870+87)÷87
125×8.8 1.3+4.25+3.7+3.75 17.15-(3.5-2.85)
3.4×99+3.4 4.8×1.01 0.4×(2.5÷73)
(1.6+1.6+1.6+1.6)×25
12.3-2.45-5.7-4.55 2 + 0.125×0.25×64
64.2×87+0.642×1300 78×36+7.8×741-7
0.125× +0.5 2.42 +4.58 -43×0
25÷100 4.25-3 -(2 -1 )
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
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
2004/2003*2005
=(2004/2003)*(2003+2)
=2004+4008/2003
276*543-267/276+543*275
=543*(276+275)-267/276
=543*551-267/276
17/51+ (68/1+51/2)*17
五十二和二十五十壹× 79.45+159× 47.56+79和二十五十壹× 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
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(從3-2002***2000，有1000個二)+2+1。
=1000×2+2+1
=2003
5兩個問題都用了壹個換算公式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×
(1×2) +(2×3) +(3×4)+...+(10× 11)
=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
三分之壹+十五分之壹+三十五分之壹+六十三分之壹+九十九分之壹。
=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
壹又六分之五+七十二-九二十+十壹三十-十三四十二+五十六。
(根據提示，1和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
1.7+150 +3.98 17.625-(4.4+58 ) 3.35×6.47×2+6.7×3.6
125×(8+0.8+0.08) 910 ×(56 -49 ÷45 )
2.8×0.4+10.2÷3.4 35 ÷〔78 -(25 +38 )〕 18.7-3.375-6.625
(9+92+93)×0.01 13.5×[1.5×(1.07+1.93)]