How many numbers from 1 through 200 have a 2 in the units place and are divisible by 4?
I want to find the numbers that have a 2 in the units place, so they must end in 2. Then, I want to check which of them are divisible by 4. A number is divisible by 4 if its last two digits are divisible by 4. So, I can ignore the other digits and just focus on the tens and units digits. There are 10 such pairs, so there are 10 numbers from 1 through 200 that satisfy the given conditions. 