ex.5.9.5.c

#include <stdio.h>

int main (void)
{
	int n, number, triangularNumber, counter;

	counter = 1;
	while ( counter <= 5 ) {
		printf ("What triangular number do you want? ");
		scanf  ("%i", &number);

		triangularNumber = 0;

		n = 1;
		while ( n <= number ) {
			triangularNumber += n;
			++n;
		}

		printf ("Triangular number %i is %i\n\n", number, triangularNumber);
		++counter;
	}

	return 0;
}