Answer:
28
Step-by-step explanation:
It can be a one digit no.
_
2C1 = 2 (only two even options available)
It can be a 2 digit no.
_ _
The last digit has to be even for the no. to be even.
2C1 × 4C1 = 8 (2C1 for the last digit, 4C1 for the first)
It can be a 3 digit no.
_ _ _
First digit has to be less than 5 to be less than 500, and the last digit has to be even.
1) 2/4 _ 4
2C1 × 3C1 = 6 (2C1 to choose between 2 and 4, 3C1 for the second digit)
2) 1/3 _ 2/4
2C1 × 3C1 × 2C1 = 12 (2C1 to choose between 1 and 3, 3C1 for the second digit, 2C1 to choose between 2 and 4)
Total = 2 + 8 + (6 + 12)
= 28
