Modulo operator in Objective C

From the "Programing in Objective C" (Kochan):

Program 5.8 prompts the user to enter a number and then proceeds to display the digits from that number from the rightmost to leftmost digit.

// Program to reverse the digits of a number
#import <Foundation/Foundation.h>

int main (int argc, char *argv[])

{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int number, right_digit;

NSLog (@"Enter your number.");
scanf ("%i", &number);

while ( number != 0 ) {
right_digit = number % 10;
NSLog (@"%i", right_digit);
number /= 10;
}

[pool drain];
return 0;
}

My question is: what happening when user types in single digit number- 1 to 9 ? I couldn't find any material about such case. After compilation the program just proceed with returning that single digit. Why is that? I was trying to come up with code for this task and spend literally 2 hours, trying to incorporate loops and decision making for this " if number is single digit" problem. And the solution was so ignorant!