6.42x1.1-6.42简便运算

（224+1/222）x1/223=(223+1+1/222)x1/223=(223+223/222)x1/223=1+1/222=223/222;1/128+1/64+1/32+...+1/4=1/

把(90+1/88）变成“89＋89/88”,变一变就简便.(90+1/88)x1/89=（89＋89/88）×1/89=89×1/89＋89/88×1/89=1＋1/88=1又1/88

3.6x1.25十0.32/0.4=0.45x8x1.25+16/20=9/20x1+16/20=25/20=5/4

=91*1/17+9/17-1/17*100=91*1/17+1/17*9-1/17*100=1/17*（91+9-100）.（乘法分配律）=1/17*0=0

1.1x1.1x1.1-1.1x1.1-0.11=1.1x1.1x1.1-1.1x1.1x1-0.11x1=1.1x1.1x(1.1-1)-0.11x1=1.1x1.1x0.1-0.11x1=1.1x

(38+1/36)x1/37=[(37+1)+1/(37-1)]*/37=[(37+1)(37-1)+1]/36*1/37=(37^2-1+1)/36*1/37=37^2/36*1/3737/36

1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/9-1/7=1-1/7=6/

1/17x4/9+5/17x1/9=1/17x4/9+1/17x5/9=1/17x(4/9+5/9)=1/17x1=1/17

8.8x1.25=(8+0.8)x1.25=8x1.25+0.8x1.25=10+1=11

41.2×8.1+11×9.25+53.7×1.9=41.2×8.1+11×9.25+(41.2+12.5)×1.9=41.2×8.1+41.2×1.9+11×9.25+12.5×1.9=41.2×(

41.2x8.1+11x1.25+53.7x1.9=41.2x8.1+1.1x12.5+41.2x1.9+12.5×1.9=41.2×（8.1+1.9）+（1.1+1.9）×12.5=41.2×10+

1.1x1.1x1.1-1.1x1.1-0.1=1.1×1.1×（1.1-1）=1.1×1.1×0.1-0.1=0.121-0.1=0.021

1x1\3=1/2*(1/1-1/3)2x1\4=1/2*(1/2-1/4).1x1\3+2x1\4+3x1\5+.+2006x1\2008=1/2(1/1-1/3+1/2-1/4+1/3-1/5+.

41.2x8.1+11x1.25+53.7x1.9=41.2x8.1+11x1.25+(41.2x1.9+12.5x1.9)=41.2x(8.1+1.9)+1.25x(11+19)=412+37.5=

您好：35.55x1.4+(25.2-24.57)=49.77-24.57+25.2=25.2+25.2=50.48/15÷【8/3-（7/4+5/6）】=8/15÷(32/12-21/12-10/1

1.(5/4)×25×4×5×).4=(5/4×4×5)(25×0.4)=1×10.=10.1-0.1×1/10+10%÷0.1=1-0.01+(0.1÷0.1).=1-0.01+1.=2-0.01=

4.9x(1+0.02)=4.9+0.049*2=4.998

因为1/[n(n+2)]=1/2*[1/n-1/(n+2)]所以1/4x1/6+1/6x1/8+1/8x1/10+1/10x1/12=1/2*(1/4-1/6+1/6-1/8+1/8-1/10+1/1

Xn/（x1+x2+...Xn-1)(X1+X2...+Xn）=1/(x1+x2+...+xn-1)-1/(x1+x2+...+xn-1+xn)所以原式=1/x1-1/(x1+x2)+1/(x1+x2

＝1.1×1.1×（1.1-1）-0.11＝1.1×1.1×0.1-0.11＝0.11×（1.1-1）＝0.11×0.1＝0.011