All Sudoku Variants
9×9 · Arithmetic

Double Arrow Sudoku

A line with a circle at each end; the digits on the line between the circles sum to the total of the two circled digits.

2 931468

An example Double Arrow puzzle: the digits between the circles sum to the two circled ends — 1 + 4 + 6 = 3 + 8.

Double Arrow Sudoku draws a line with a circle at each end. The rule balances the two: the digits on the line between the circles must add up to the sum of the two circled digits. It is a neat twist on Arrow Sudoku, where a single circle holds the total — here the total is shared between two ends.

The rule: the line equals the two circles

Add the two circled digits; the cells along the line between them must add to the same amount. Below, the circles hold 3 and 5 (sum 8), and the two line cells 2 and 6 also add to 8.

◯326◯5

Circles 3 and 5 add to 8; the line cells 2 + 6 = 8 match them.

A worked example, step by step

Suppose the two circles are already solved as 3 and 5, and the two line cells between them are still empty.

◯3◯5

Step 0. Circles 3 and 5 are placed; the two line cells are empty.

Step 1 — total the circles. Add the ends: 3 + 5 = 8. That is exactly what the two line cells must add up to.

◯3line must total 8◯5

Step 1. The two circles add to 8, so the line must total 8.

Step 2 — list the pairs. Two different digits that add to 8 are {1,7}, {2,6} or {3,5}. Since the row already contains a 3 and a 5 (they are in the circles), that pair is out — leaving {1,7} or {2,6} for the line, a sharp reduction from one balance.

◯31/27/6◯5

Step 2. The line is {1,7} or {2,6} — the {3,5} pair is ruled out by the circles.

Solving strategy

  • Solve the circles first when you can. Two known ends give the line an exact target sum.
  • Work it backwards too. If the line cells are known, their total fixes the sum the two circles must share.
  • Rule out repeats. Digits already used on the same line, or forced by the circles, trim the list of valid pairs fast.
  • Treat it as a cage. Once the target is set, the line is a small sum — the same combination logic as Killer.

Common mistakes

  • Including the circles in the line sum. Only the cells between the circles add to the total; the circles are the target, not part of it.
  • Assuming the ends are equal. The circles need not match each other — only their sum ties to the line.
  • Allowing an impossible repeat. Line digits can only repeat across different rows, columns and boxes.
  • Forgetting ordinary Sudoku. Every cell still obeys its row, column and box.

Can I play it here?

Not yet — Double Arrow Sudoku isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile: