Question 23
Dan entered the numbers 1 to 9 in the cells of a 3 × 3 table. He began by placing the numbers 1, 2, 3 and 4 as shown in the picture. It happened that for the number 5, the sum of the numbers in the adjacent cells (having a common side) is equal to 9. What is the sum of the numbers adjacent to the number 6?
