Question 4
Twenty-seven digits consisting of 1, 2, 3, 4, 5, 6, 7, 8 and 9 are each to be filled in and arranged in a row of boxes such that each digit is exactly used three times. There is another digit between the first 1 and the second 1, and another digit between the second 1 and the third 1. There are two other digits between the first 2 and the second 2, and two other digits between the second 2 and the third 2. The same applies to the other digits, so that there are nine other digits between the first 9 and the second 9, and nine other digits between the second 9 and the third 9. The middle seven digits are 7469258. Complete the boxes below.
