Write a program that reads in a positive integer N and calculates and displays the sum of the first N even integers. For example if N is 6, the program should display the value 42, which is: 2+4+6+8+10+12=42.
Caution: You need to write a program to do the addition. If you happen to know that the answer is always N*(N+1) and then just output the result, you will get 0 credit.

thank you.

Seems like a simple for loop should do the trick, no? Show us what you've tried and we can help if you get stuck.

David

## All 3 Replies

Seems like a simple for loop should do the trick, no? Show us what you've tried and we can help if you get stuck.

David

It seems like I have correctly finished the problem, see below:

``````#include "stdafx.h"
#include "simpio.h"
#include "genlib.h"

int _tmain(int argc, _TCHAR* argv[])
{
int num,nom,i,nam;
printf("Enter a even integer: ");
num=GetInteger();
nom=0;
for(i=2;i<=num*2;i+=2)
{
nam=i;
nom=nom+nam;
}
printf("The sum of the first %d even integers is %d.\n",num,nom);
return 0;
}``````

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I would greatly appreciate it if anybody can catch some small errors in this problem.

The variable nam seems to be unneeded. You can replace the lines

``````nam=i;
nom=nom+nam;``````

in the for loop with simply

``nom+=i;``

Besides that, it seems fine (though I'm not sure why you're using printf instead of cout in a c++ program)

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