Every row is a 10-frame game of bowling, and the number to its left is the row's score.

• An X is a strike: all 10 pins on the first throw of a frame. It scores 10 plus the next two throws.
• A / is a spare: the second throw knocks down the pins the first throw left. It scores 10 plus the next throw.
• Any other frame is two digits that total 9 or less, and it scores their total.
• There are no bonus throws after the last frame, so a strike or spare near the end of a row only counts the throws left in that row.

It's also a sudoku: every row, column and 4×4 box has the digits 0–7 once each. The strikes and spares are already in place; fill in the digits so every row hits its score. In this row, frame 1 is 7 then a spare: 10 plus the next throw (a strike, 10) = 20. Frame 2 is a strike: 10 plus the next two throws (2 and 5) = 17, so 37. Frame 3 is open: 2 + 5 = 7, so 44, and so on to 157.

Use the scoresheet above the grid: tap any cell in a row to see that row frame by frame, with the running total as far as it can be worked out.

Start with ordinary sudoku logic. Each row, column and box has only eight digits, so a few placed digits rule out a lot.

Open frames can't reach 10, so a 7 can only share an open frame with 0, 1 or 2, and a 6 with 0 to 3.

Once a row has only a few empty cells, its score usually settles them. Strikes and spares double-count the throws after them, so the cells right after an X or a / matter most.