Kropki Sudoku rules and puzzles

The case notes

Find the partner across a dot or marker

A dot or letter gives the two cells a relationship. The useful question is: which partner can still fit? Watch a worked example, then try the idea in a puzzle.

Put it into practice

Which partner still fits?

A dot or letter gives the two cells a relationship. The useful question is: which partner can still fit?

No partner for 5, 7 or 9

This black dot needs one digit to be double the other. Neither cell can hold five, seven or nine: none has a double or half among the digits one to nine.

X: only 4 + 6 remains

Now the X. These two cells add to ten. This row already has one, two, three, eight and nine. That removes every ten-pair except four and six. Five plus five repeats a digit, so it cannot work either.

The column chooses the order

There is a six above the right-hand cell. Its column rules out six here, leaving four on the right and six on the left.

Mark → partners → Sudoku check

The mark finds the possible partners. Ordinary Sudoku rules remove the pairs or positions that cannot fit.

Read the transcript

A dot or letter gives the two cells a relationship. The useful question is: which partner can still fit? This black dot needs one digit to be double the other. Neither cell can hold five, seven or nine: none has a double or half among the digits one to nine. Now the X. These two cells add to ten. This row already has one, two, three, eight and nine. That removes every ten-pair except four and six. Five plus five repeats a digit, so it cannot work either. There is a six above the right-hand cell. Its column rules out six here, leaving four on the right and six on the left. The mark finds the possible partners. Ordinary Sudoku rules remove the pairs or positions that cannot fit.

Keep following the clues