Can you represent an eight digit number with a five digit number?
Not in a way that would be generally understood. However, it is
possible.
An 8-digit number in base 10 can be represented by a 5-digit
number in base 32. For example, extending the scheme for labeling
digits for base 32,
VVVVV32 = 3355443110
Similarly, the 8-digit number 33333333 in base 4 is the 5-digit
number 65535 in base 10