For each number from 0 to 99, Andrew wrote down the product of its digits. What is the mean of the numbers andrew wrote down?
assuming single digit numbers are written without the leading zero
the mean is:
1+2+⋯+9+1⋅1+1⋅2+⋯1⋅9+2⋅1+2⋅2+⋯2⋅9+⋯⋯9⋅1+9⋅2+⋯9⋅9100=45+1(45)+2(45)+⋯+9(45)100=45⋅46100=20.7
