Cross Inverse

Object of the Game

To place all given Equas into the shaded result fields so when three adjacent numbers in the grid are calculated together they result in the placed Equas for both row and column.

How to Play

• Choose a prefilled number grid.
• Calculate the prefilled numbers in adjacent threes.  
• Numbers can be calculated in any combination, but keep in mind the mathematical order of operations as you calculate:
  • First perform any calculations inside parentheses, if they exist.
  • Next perform all multiplications and divisions
  • Lastly, perform all additions and subtractions
• For this game, adjacent numbers are three numbers connected horizontally or vertically only, as shown in the diagrams below. No “L” shape is allowed.

• Calculated numbers should satisfy the result for both row and column.
• Use only basic arithmetic functions: addition, subtraction, multiplication, division; and follow the order of operations when necessary.
• In some larger grids of Cross Inverse, you will have empty result fields on both the left and ride side of the puzzle to solve.

Example

Insert Equas 15, 16, 18 and 21 into the shaded boxes in this CM8 shape so all horizontal and vertical three numbers give that result when they are added, subtracted, multiplied, or divided together using the order of operations. The solution is as follows:

Let’s check the solution:
3 x 9 – 6 = 21
11 + 11 – 4 = 18
4 * (9 – 5) = 16
11 + 7 – 3 = 15