2 solution C b

#include <stdio.h>

int help(int num)
{
    if (num>9)
        return 10*help(num/10);

    return 1;
}

int func(int num)
{
    if(num<10)
        return num;

    return func(num/10)+(help(num)*(num%10));
}

void main()
{
    int num = 54321;
    printf("%d\n",func(num));
}