What number is 900 more than the greatest possible 4-digit even number that can be made using the digits 1, 4, 2, and 5?

To make it even, the last digit has to be 4 or 2.

To make it the largest, it has to start with 5.

5412 is the largest even? Can you make a larger?

I'not sure.

To find the greatest possible 4-digit even number using the digits 1, 4, 2, and 5, we need to arrange these digits in descending order and make sure the last digit is even.

Let's start by arranging the given digits in descending order: 5, 4, 2, 1.

Next, we need to make sure the last digit is even. Since the digit 5 is the last digit, which is odd, we need to swap it with the next largest even digit, which is 4.

So the arrangement becomes: 4, 4, 2, 1.

Now we have the greatest possible 4-digit even number, which is 4421.

To find the number that is 900 more than this, we simply add 900 to 4421.

4421 + 900 = 5321.

Therefore, the number that is 900 more than the greatest possible 4-digit even number using the digits 1, 4, 2, and 5 is 5321.