First, we should list two numbers that will get the product 32 that will match the requirements.
1 x 32
2 x 16
4 x 8
Now, we can only see that the 1 x 32, and 2 x 16, when the addends are combined to form a new numbers are three-digit numbers and don't sum-up with 12. But there is, it is 4 x 8 when combined is 12, the product is 32, both multiples of 4, and rounds off to 50. (I know it is just a typo-error that you typed 5 instead of 50)
So therefore, 48 is the answer.
