Originally Posted by

**novice123** I have 3 columns, each with 12 slots, containing different numbers of balls.

Column A has 3 balls, giving a total of 220 different combinations of balls within the column itself.

Column B has 4 balls, giving a total of 495 combos within the column.

Column C has 5 balls, giving a total of 792 combos within the column.

I place column 1 and 2 next to each other (parallel). I now have to place the balls in the 2 columns in **all possible combinations** without placing any balls in direct opposite slots. In other words, if the slots are named A-1, A-2 etc., I can not place a ball in B-1 if A-1 already contains a ball. Remember column A should always contain 3 balls and column B always 4 balls. How many combos are possible in this scenario, and what is the formula for the calculation?