The object of CrossSum is to fill in the number fields with the digits 1 through 9, and have the six mathematical equations be correct, all at the same time.

The puzzle grid has nine slots for numbers, 12 mathematical operators and six precalculated results. In some of the earlier puzzles either one or two of the digits are prefilled.

The player must use two digits to formulate the equation of X + 6 x Y = 45.

IMPORTANT NOTE:

Don't tell your fourth grade math teacher this but in CrossSum you do NOT follow the rules of Order of Operations. Normally in this example you would solve for X and Y so that X + (6 x Y) = 45. This is because in real life in the absence of parentheses, multiplication and division happen before addition and subtraction.

Not In CrossSum

In CrossSum you add whatever is put in the first digit to six and then multiply the resulting sum by another number to get 45.

Two possible solutions to this line, based on being given six, the two operators and the result of 45 are:

3 + 6 x 5
-or-
9 + 6 x 3

In the real world, these two equations would result in 33 and 27 respectively. In the land of CrossSum, both result in 45.

If you can find a spot for all 9 digits that mean each of the six equations are true, then you have solved that particular puzzle.

As it goes on, the difficulty increases with lower result numbers and no answers being pre-filled in.

Enjoy!