Bai2.2_TongcapsoCong.c

#include<stdio.h>
int main() {
	unsigned int n;
	printf("Nhap so tu nhien n: \n");
	scanf("%d", &n);
	unsigned int sum = 0;
//	unsigned int i =1;
//	for(;i<= n; i++){
//		sum += i;
//	}
	sum = (n + 1)*n/2;
	printf("SUM = %d", sum);
	return 0;
}