C++ :

#include<iostream>
using namespace std ;
int main ()
{
	int sum=0,a;
	for(a=1;a<=100;a=a+1)
		sum=sum+a;
	cout<<sum<<endl;
	return 0;
}

Pascal :

var a,b:integer;
begin
b:=0;
for a:=1 to 100 do
begin
b:=a+b;
end;
writeln(b);
end.

Java :

public class Main
{
    public static void main(String [] args)
    {
       int i;
       int sum;
	   for (i = 0,sum = 0;i < 101;i ++)
	   {
		   sum = sum + i ;
	   }
	   System.out.print(sum );
    }
}