Separating Digits With Modulus?

The following code splits an integer into separate digits. It then adds 7 to each of those digits, and then finds the remainder when the result is divided by ten. To do this it uses the Modulus operator.

public class manipulateIntegers {
public manipulateIntegers() {
System.out.println("Enter a four digit Integer");
String y = System.console().readLine();
int[] list = new int[5];

[code].....

I understand completely about what modulus does vis-à-vis fetching the remainder, but I don't understand why using the modulus operator gets you each digit individually?

for example, this snippet splits the digits of an integer - but how??

int number; // = some int
while (number > 0) {
print( number % 10);
number = number / 10;
}

and why does number have to be reassigned as number / 10?