Using the digits $0,2,4,6,8$ not more than once in any number, the number of 5 digit numbers that can be formed is 

The digits are $0,2,4,6,8$

The number of 5 digit numbers using the digits $0,2,4,6,8$ with out repetition is equal to number of ways of filling all five blanks with five digits, and do not fill zero in the first blanks

The first blank can be filled with any one of $2,4,6,8$, this can be done in 4 ways. 

The remaining four blanks can be filled with the remaining four digits in 4! ways

Therefore, the number of 5 digit numbers is $4·4!=\boxed{96}$