Question

int main (int argc, const char * argv[])
{

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    int n, number, triangularNumber;
    NSLog(@"What Triangular Number Do You Want?");
    scanf(@"%i", &number);
    triangularNumber = 0;

    for (n = 1; n <= number; ++n)  
        triangularNumber += n;
        NSLog(@"Triangular Number %i is %i", number, triangularNumber);

    [pool drain];
    return 0;
}

The output when I write an integer is this:

Triangular Number 0 is 0

Answer 1

Your input number is 0, and your condition in the for loop starts at 1. Therefore, the loop is never executed.