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1x3x5

1/1x3x5+1/3x5x7+1/5x7x9+…+1/95x97x99 =1/4(1/(1*3)-1/(3*5)+1/(3*5)-1/(5*7)+.....+1/(95*97)-1/(97*99) = (1/4) ( 1/(1x3) - 1/(97x99) = (1/4) (1/3 - 1/9603] =800/9603

Visual Basic Dim a As Integer, sum As Integersum = 1For a = 1 To 99 Step 2 sum = sum * aNext a Print "1*3*5*...*99="; sumC int a,sum;for(a=1,sum=1;a

an=1/[(2n-1)(2n+1)(2n+3)] =(1/4) { 1/[(2n-1)(2n+1)] -1/[(2n+1)(2n+3)] } Sn =a1+a2+...+an 1/(1x3x5)+1/(3x5x7)+1/(5x7x9)+...+1/(95x97x99) =S48 = (1/4) ( 1/(1x3) - 1/(97x99)] = (1/4) (1/3 - 1/9603] =800/9603

1/1x3-1/97x99=9600/28809 不知道对不对 可以分解为An=1/(2n-1)(2n+1) -1/(2n+1)(2n+3) 1/3-1/3x5+1/3x5-1/5x7.............+1/97x99=上面第一行的答案

末三位数是 000

其实找到了规律就很简单。 1x3x5=15,末位是5, 15x7=105,末位是5, 105x9=945,末位是5, 945x11=10395,末位是5, 10395x13=135135,末位是5. 可得接下来的积末位数字都是5 所以1x3x5x7`````x1991的末位数字是5. 望提问者采纳,谢谢!

#include void main(){int i,j;i=0;j=1;for(i=3;i

分析:1/1x3x5=1/4×(1/1*3 -1/3*5) 1/3x5x7=1/4×(1/3*5 -1/5*7) 1/5x7x9=1/4×(1/5*7 - 1/7*9) 1/7*9*11=1/4×(1/7*9 -1/9*11) ..................... 1/2003x2005x2007=1/4×(1/2003*2005 -1/2005*207) 所有的等式相加有 1/1x3x5+1/3x5x7+1/5x7x9+....

这个算法,现有的整形变量都会溢出。需要使用高精度整数处理,所以写一个加法的给你。 C语言的 s=0; for(i=1;i

(1+2015)×1008÷2 =2016×504 =1016064

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