195783

in conclusion the way to work out how to add to 200 is you have any number in the top left square and a different number in the top right. on the bottom left you must have the exact same number as the top right and the next number can be any number. example: top left=6; top right=3; bottom left=3; bottom right=7. this equals 200. its easy to find out if an answer is odd or even because odd+odd=even; even+odd=odd; odd+even=odd and even+even=even.