Something like this?
Here is a grid of four "boxes":
Square divided into four.
http://nrich.maths.org/content/02/09/penta2/square1.gifYou must choose four different digits from 1−9 and put one in each box. For example:
http://nrich.maths.org/content/02/09/penta2/square2.gifThis gives four two-digit numbers:
52 (reading along the 1st row)
19 (reading along the 2nd row)
51 (reading down the left hand column)
29 (reading down the right hand column)
In this case their sum is 151.
Your challenge is to find four different digits that give four two-digit numbers which add to a total of 100.
Something like that?