There were celebrations in one household this afternoon, when a man who started a Sudoku puzzle from the newspaper nearly 18 months ago but stopped trying to complete it when it became rather too difficult, made a chance inroad which may, ultimately, lead to its solution.
Moys Kenwood, 57, began the giant 5×5 puzzle published in the Hull Daily Mail on the 29th August 2019, at his mother's home in Hull, England, but struggled from the start.
Each of the 25 large squares contain 25 cells, and must be completed using the letters K to Z, and the numbers 1 to 9. Instead of the regular 81 Sudoku cells, the giant puzzle requires 625 cells to be filled.
Kenwood pored over the grid for hours, days, weeks, and months, until he was sure he wouldn't be able to progress any further, and put it with some other papers in a storage box. On Sunday, however, searching for something in the box, he spied the Sudoku, and decided to give it another shot.
The breakthrough came almost immediately, as, looking at Square 17, he saw that letter Z could ONLY be entered into cell number (reading from top to bottom, left to right), because vertically, Square 2 already had a Z in column 2, Square 7 already had a Z in column 1, Square 12 already had a Z in column 3, and Square 22 already had a Z in column 5. This meant that the Z in Square 17 had to be in column 4!
At this point in time, the number 4 in cell number 14 of Square 17 had not yet been entered, and so the column 4 cell numbers 14, 19, and 24 were empty. Z had to go in one of those!
It couldn't go in cell number 14, in row3, because there was already a Z in row 3, in Square 16 (in cell number 12, for those interested), and it couldn't go in cell number 19, in row 4, because there was already a Z in row 4, in Square 19 (in cell number 20), so the only cell left for it to go into in row 4 of Square 17 was cell number 24!
Kenwood was overjoyed!
With this discovery, and because there was already a Z in row 1 of Square 20 (cell number 4), another in row 4 of Square 19 (cell number 20), one in row 2 of Square 18 (cell number 8), and the newly-discovered Z in row 5 of Square 17 (cell number 24, remember?), the Z in Square 16 had to be in row 3!
Row 3 of Square 16 then had two empty spaces: in column 2 and column 5 - cell numbers 12 and 15 respectively. However, looking up, Kenwood could see that, in Square 6, row 5, in cell number 10, there was already a Z! This meant that Square 16's Z had to be in row 3 column 2 - cell number 12!
He carefully wrote it in. Now he was on a roll.
Vertically, Square 1 had a Z in column 3, at cell number 8; Square 6 had a Z in column 5, at cell number 10; Square 16 now had its Z in column 2, at cell number 12. This left either column 1 or column 4.
Square 21, at the bottom left corner, could not have Z in column 4, because of other Zs on row 2 in Square 22, and on row 3 in Square 24. This meant that Square 21's Z had to be in column 1, and that of Square 11 had to be in column 4.
It was getting exciting!
There were two empty spaces on column 4 - the cells at cell number 4, on row 1, and at cell number 24, on row 5. Looking to the right, Kenwood saw that Square 12, next door, already had a Z on row 5, in cell number 23, and this settled it! The Z in Square 11 had to be in row 1, at cell number 4!
Now he was cooking!
His eyes fell upon the number 5 in Square 2, in column 1. Looking vertically, Square 7 had a 5 in column 5, Square 12 had a 5 in column 3, and Square Square 22 had one in column 2. That meant the number 5 in Square 17 had to be in column 4. In that column, there were two free spaces, in row 1, at cell number 4, and in row 4 at cell number 19. Further aling that row, in Square 18, there was already a 5, so Square 17's number 5 had to go in row 1, at cell number 4.
Two more discoveries followed: a Y in Square 17's cell number 3, and an S in Square 20, at cell number 20.
"It's not everybody's 'cup of tea', but I like Sudoku, and it's true what they say about patience and persistence."