Difference Sudoku

Use the differences to find the solution to this Sudoku.
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem

 Difference Sudoku printable worksheet



By Henry Kwok

 

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Difference Sudoku

 

 

Rules of Difference Sudoku



Like the standard Sudoku, the object of the puzzle is to fill the whole $9 \times 9$ grid with numbers from $1$ to $9$, so that each row, each column, and each of the nine $3 \times 3$ squares contain all nine digits.

There are special clue-numbers placed on the border lines between selected pairs of adjacent squares of the grid. Each clue-number is the difference between the two numbers in the adjacent squares.

For example, a clue-number $7$ on the border line between two adjacent squares means that the possible pairs of numbers for the squares on either side must be one of the following combinations: $1$ and $8$, $8$ and $1$, $2$ and $9$, or $9$ and $2$.

The inequality sign indicates that the number in row 5 column 7 is smaller than the number in row 5 column 8.

As this variant has only one inequality sign on the border line, it is called Minimal Difference Sudoku.