Average of all 6 digit numbers that contain only digits $1,2,3,4,5$ How do I find the average of all $6$ digit numbers which consist of only digits $1,2,3,4$ and $5$?
Do I have to list all the possible numbers and then divide the sum by the count? There has to be a more efficient way, right?
Thank you!

Don't want to completely give it away, but there are $5^6$ of these numbers as the first through sixth digits can all take on five different values.  I'm sure there's something slicker you could do, but it should be easy to then sum them all up by evaluating the sum
$$
\sum_{a=1}^5 \sum_{b=1}^5 \sum_{c=1}^5 \sum_{d=1}^5 \sum_{e=1}^5 \sum_{f=1}^5 (a \cdot 10^5+b \cdot 10^4+ c \cdot 10^3+d \cdot 10^2+ e \cdot 10^1 + f \cdot 10^0)
$$
and dividing by the total number of them.
