A 3x3 square grid must be filled with numbers 1,2,3 in such a way that the sum of numbers in every line and column is a multiple of 3. How many different ways are there? The possible solutions are a) 54 b) 81 c)

A 3x3 square grid must be filled with numbers 1,2,3 in such a way that the sum of numbers in every line and column is a multiple of 3. How many different ways are there? The possible solutions are a) 54 b) 81 c)