So the way you brute force stuff like this is that you make a program repeatedly enter numbers, starting with 0 and increasing each time (1, 2, 3, etc.) until it eventually gets the right number by entering every possible combination. Infinite Monkey Theorem.
You're supposed to make the number stupidly big so that a brute force program takes so long to find the correct number that it's either impossible or you can simply change the number by the time they find it.
If the number it has to find is literally single digit, your security can be broken through via brute force in a matter of
seconds.
This is part of how websites determine whether or not your password is "strong". How long would it take a machine entering every possible combination of letters and numbers to eventually land on your password if it starts from 0 and works its way up?