10929 - You can say 11

#include<stdio.h>
#include<string.h>

char num[1005];

int main()
{
    int i,n,l;
    //freopen("in.txt","r",stdin);

    while(gets(num)&&strcmp(num,"0"))
    {
        n=0,l=strlen(num);

        for(i=0;i<l;i+=2)
            n=n+(num[i]&15);

        for(i=1;i<l;i+=2)
            n=n-(num[i]&15);

        if(n%11)
            printf("%s is not a multiple of 11.\n",num);
        else
            printf("%s is a multiple of 11.\n",num);
    }
    return 0;
}