How many 6-digit numbers can be formed using the digits 23456 and 8 with repition?

Order does matter in this case so you need to use the formula for a Permutation with repetition allowed.

This would be n^r where

n=6 different numbers and

r=6 possible places for each number to go when forming the full 6-digit number.

6^6 = 46,656 possible digits