ex.8.2B.c

#include <stdio.h>

int calculateTriangularNumber (int n)
{
	int i, triangularNumber = 0;

	for ( i = 1; i <= n; ++i )
		triangularNumber += i;

	return triangularNumber;
}

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

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

		triangularNumber = calculateTriangularNumber(number);

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

	return 0;
}