The median of four numbers is 48. Three of the four numbers are 42, 51 and 52. What is the other number?

The answer would be 45.

To find this, I multiplied 48 by 2 (since there is an even amount of numbers, the median would be the mean/average of the two middle numbers) and got 96.

Then, I assumed that the middle numbers would have to be 51 and the unknown number.

Finally, I subtracted 51 from 96, getting 45 as the unknown number.

The other number would be 12.