Dear sudoku solvers: With this month’s puzzle, we highlight a curious thing about the number nine, which as you know occurs in every sudoku puzzle exactly nine times. Take any whole number (other than zero) and multiply it by 9. Then add up all of the digits. If the sum is greater than nine, then add up all of its digits, and so on. Eventually you will get a sum of 9.
Let’s try it out:
Take the number 43 and multiply it by nine: 43 × 9 = 387.
Now let’s add up all the digits in 387: 3 + 8 + 7 = 18.
Since 18 is greater than 9, let’s add the digits in 18: 1 + 8 = 9.
This happens every time!
You hope you enjoy this month’s sudoku.