Doubling Sum Lines
(Published on 20. January 2026, 21:35 by mimec)
This puzzle is a bit similar to the Continuous Sums sudoku which I published last year, but this time the sums have to double along the lines.
Rules:
- Normal sudoku rules apply.
- Box borders divide the blue lines into segments. Digits within each segment must sum to values which increase in 2:1 ratio along the line. Every visit to a region counts to a new total.
For example, 4-125-79 is a valid sequence of digits along a doubling sum line, because the sums of digits in the segments are 4, 8 and 16:
Note: The starting and ending sum and the direction in which the sums increase must be determined by the solver. They can be different for each line.
Solution code: Row 5
Comments
on 29. January 2026, 22:25 by dawidk
Math puzzle = Good puzzle. Great math puzzle = Fantastic puzzle!
on 28. January 2026, 20:02 by miranda_9
Very nice. Love doing the math and eliminating the possibilities, that don't work. It was not hard but fun.
on 28. January 2026, 19:58 by MiguelMunoz
Good challenging puzzle. The key was figuring out where to make reasonable guesses that I could quickly narrow down. (But I still don't understand the rule that says "Every visit to a region counts to a new total." Huh? Region?)
on 28. January 2026, 18:11 by jez9999
Hate this puzzle. Feels very brute force, not a natural solve at all. Very hard.
on 26. January 2026, 21:28 by dzamie
Pretty fun, very tricky, but still doable (with a LOT of careful notes).
on 26. January 2026, 21:25 by MrWhite2020
The end logic seemed a bit brute force for the 3-1 line in box 7. Or I am missing some logic
on 22. January 2026, 23:43 by VitP
easier than it looks, because the lines are strongly forced
on 22. January 2026, 00:25 by Ragna
Very fun puzzle! Thank you. :-)
on 21. January 2026, 09:22 by Snookerfan
Fun puzzle, thanks!
on 21. January 2026, 00:28 by Qodec
Cool idea, very nice execution!
