Problem with C program not exiting at integer count 150 by using a while loop

Question

I was wondering if I could get some help with a problem that I am having.

Basically, I am trying to end my program by using a while loop when the people count gets to 150.

My math seems to be right, but for some reason, the program ends when it gets to people count 276.

Can anyone help with this issue? Thanks!

Code Input:

int main () { 
    // declare variables
    int weeks=0, people=5;
    while (people < 150) {
        weeks++;
        people=(people-weeks)*2;
        printf("On week %d Professor Rabnud's Social Media Group has %d people\n", weeks, people);
    } 
    // end program
    return 0; 
}

Code Output:

On week 1 Professor Rabnud's Social Media Group has 8 people
On week 2 Professor Rabnud's Social Media Group has 12 people
On week 3 Professor Rabnud's Social Media Group has 18 people
On week 4 Professor Rabnud's Social Media Group has 28 people
On week 5 Professor Rabnud's Social Media Group has 46 people
On week 6 Professor Rabnud's Social Media Group has 80 people
On week 7 Professor Rabnud's Social Media Group has 146 people
On week 8 Professor Rabnud's Social Media Group has 276 people

Answer 1

int main () { 
    // declare variables
    int weeks=0, people=5;
    while (people < 150) {
        weeks++;
        people=(people-weeks)*2;
        printf("On week %d Professor Rabnud's Social Media Group has %d people\n", weeks, people);
    } 
    // end program
    return 0; 
}

As you can see, when week == 7 then people == 146 Because 146 < 150 is true , the loop is executed again. First, it increment week so now week == 8 , then, it caculated people . (146 - 8) * 2 == 276 , so people is now 276 Then it executed the printf() statement. Only now, 276 < 150 is false , then the loop terminated.

Because we know when week == 1 then people == 8 we can do this:

int main () { 
    // declare variables
    int weeks=1, people=8;
    while (people < 150) {
        printf("On week %d Professor Rabnud's Social Media Group has %d people\n", weeks, people);
        weeks++;
        people=(people-weeks)*2;
    } 
    // end program
    return 0; 
}