➗ How to play Ratio Sudoku
By Miguel Arechaga
Ratio Sudoku is a dot-based variant similar to Kropki but centered on multiplication. A dot with a number appears between certain cells, telling you how many times one cell divides into the other. It's a very logical and satisfying variant. Here are the rules and a few tips.
What is Ratio Sudoku?
It's a standard 9x9 sudoku where, between some neighboring cells, a dot appears indicating that one cell is an exact multiple of the other. The dot's number is the ratio: the larger value divided by the smaller one. For example, a dot with a 2 connects 3 and 6 (6 / 3 = 2); one with a 3 connects 2 and 6, or 3 and 9.
Rules and how to play step by step
- The sudoku rules apply: 1 to 9 without repeats in each row, column and 3x3 box.
- A dot between two cells means one is an exact multiple of the other; its number is the ratio.
- No dot: neither cell is an exact multiple of the other.
- You start with some clue cells and fill in the rest with logic. Every puzzle has a unique solution.
Tips to solve Ratio Sudoku
- High ratios, few options: a dot with 4 can only connect 1-4 or 2-8; one with 3, the pairs 1-3, 2-6 or 3-9. Start there.
- A ratio of 2 has more pairs (1-2, 2-4, 3-6, 4-8); use it together with the box and column to decide.
- High prime numbers: 5 and 7 almost never touch a dot (5 only with 1, 7 only with 1), so their presence or absence tells you a lot.
- Don't forget the absence of a dot: it rules out two neighbors being multiples of each other. Combine it with the classic techniques.
How it differs from regular sudoku
Compared to classic sudoku, Ratio adds multiplication relationships between neighboring cells. It's a cousin of other dot-and-mark variants where a black dot means simply double, and of variants that mix sum and difference clues. If you enjoy variants with dots and marks, you'll love these too.
