Mystery Machin Display Solved!

I knew this blog has intelligent readers. Less than three hours after the display was posted, reader Phil came up with the correct answer, a Sudoku grid.

In a Sudoku grid, the numbers in each row, column, and sub-section add up to the same total. In this case of a 9x9 grid, the total is 45. The sub-sections are the nine 3x3 grids that make up the 9x9 grid.

No number can be repeated in a row, column or sub-section.

Sudoku is presented as a puzzle, with some of the numbers filled in. The solver must fill in the rest of the numbers.

A couple of readers (one who responded by email) said this was a magic square, but it is not. In a magic square, each cell has a different number. In a 9x9 magic square, the cells contain the numbers from 1 to 81. (You can only build up to a 4x4 magic square with Machins because there is no 21p Machin that would be needed for the 5x5 square.)

Thanks to all who replied and to my friend David who sent me the image. Phil, please email me (click the Contact Larry link above) your mailing address, and I will send you the Machin prize.

--Larry

PS I don't do Sudoku puzzles. In my few spare minutes, you'll find me playing Angry Birds.