2

Part of 2023 Canadian Mathematical Olympiad Qualification

Problems(1)

numbers 1-9 in a 3x3 grid

Source: Canada Repêchage 2023/2 CMOQR

How many ways are there to fill a

3 \times 3

grid with the numbers

1

2

3

4

5

6

7

8

9

, such that the set of three elements in every row and every column form an arithmetic progression in some order? (Each number must be used exactly once)