sum=6+66+666+6666

/*sum=n+nn+nnn+nnnn  sum=6+66+666+6666*/#include <stdio.h>int fun(int s,int n){int sum=0;int tmp=0;if(s == 0||n == 0){return sum;}for(int i=0;i<n;i++){tmp=tmp*10+s;sum += tmp;}return sum;}int main(){printf("%d\n",fun(2,3));}