We do casework by the number of digits in the number.
One-digit numbers: 4 choices for the number.
Two-digit numbers: Four choices for the first digit, four for the second, for a total of 4*4=16 numbers.
Three-digit numbers: Five cannot be the first digit, since if that is the case we will have a number over 500, so we have three choices for the first digit and four for each of the others, for a total of 3*4*4=48 numbers.
This is a total of 4+16+48=68 numbers.