The case notes
Reading even and odd marks
A marked square contains an even digit. A marked circle contains an odd digit. Watch a worked example, then try the idea in a puzzle.
Put it into practice
Square: even · Circle: odd
Squares and circles are small clues with one clear job. A square means even; a circle means odd.
The row needs 7 and 8
This row already has every digit except seven and eight. Which one belongs under each mark?
Circle 7 · Square 8
Seven is odd, so it goes in the circle. Eight is even, so it goes in the square. The marks settle the pair.
Mark + Sudoku = digit
The marks tell you parity, not the exact value. Combine them with ordinary Sudoku to find the digit.
Read the transcript
Squares and circles are small clues with one clear job. A square means even; a circle means odd. This row already has every digit except seven and eight. Which one belongs under each mark? Seven is odd, so it goes in the circle. Eight is even, so it goes in the square. The marks settle the pair. The marks tell you parity, not the exact value. Combine them with ordinary Sudoku to find the digit.
