pi program

[Charanjit Singh via Digitalmars-d-learn]

import std.stdio;
import std.math;
void main()

{
     float sum,pi,t;
      int n=1;
     sum=0;
     while (n<100 )
     {
     t=1/( n*n);
     n=n+1;
     sum=sum+t;


    }
     writeln("value of PI=  " , (sum*6)^^.5);
  that is pi program as
(pi^2)/6=   1/1+  1/4  +  1/9  +  1/16  +  1/25
but output of my program is 2.44