How many even numbers less than 500 can be formed using the digits 1, 2, 3, 4 and 5? Each digit may be used only once in any number.

To solve this problem, we need to consider the different cases for the number of digits in the number.

1. One-digit numbers: The only even number we can form with one digit is 2. So, there is 1 such number.

2. Two-digit numbers: The units place must be an even number. So, there are 2 choices (2 and 4) for the units place. The tens place can be any of the remaining 4 digits. So, there are 4 choices for the tens place. Therefore, there are 2*4 = 8 such numbers.

3. Three-digit numbers: Again, the units place must be an even number, so there are 2 choices. The tens place can be any of the remaining 4 digits, so there are 4 choices. The hundreds place can be any of the remaining 3 digits, so there are 3 choices. Therefore, there are 243 = 24 such numbers.

4. Four-digit numbers: The units place must be an even number, so there are 2 choices. The tens place can be any of the remaining 4 digits, so there are 4 choices. The hundreds place can be any of the remaining 3 digits, so there are 3 choices. The thousands place can be any of the remaining 2 digits, so there are 2 choices. Therefore, there are 243*2 = 48 such numbers.

5. Five-digit numbers: The units place must be an even number, so there are 2 choices. The tens place can be any of the remaining 4 digits, so there are 4 choices. The hundreds place can be any of the remaining 3 digits, so there are 3 choices. The thousands place can be any of the remaining 2 digits, so there are 2 choices. The ten-thousands place is the remaining digit, so there is 1 choice. Therefore, there are 24321 = 48 such numbers.

Adding up all these cases, there are 1 + 8 + 24 + 48