Sudoku variant · rules and tips

Region Sum Lines

A region sum line is cut into segments wherever it crosses a box boundary, and every segment must add up to the same total. Equal shares for every box the line visits.

Get it onGoogle PlayPlay Region Sum Lines on the web
Professor Cryptic, the owl who teaches in the app
Professor Cryptic explains the rule

The Professor's tips

How do you solve Region Sum Lines?

01 / Warm up

Start on a 4 by 4 grid

  • With 2 by 2 boxes, lines cross boundaries often. Each portion within a box must sum to the same value as every other.
  • Count the cells in each segment first. If one segment holds a single cell and another holds two, that lone digit must equal the pair together.
  • A line that stays inside one box has a single segment, and a single segment constrains nothing. Study the lines that cross.
02 / Level up

Then try a 6 by 6 grid

  • The boxes are 2 by 3 here. A line crossing two boundaries is cut into three segments, and all three must share a total.
  • The shorter the segment, the harder it works. A one-cell segment forces that digit to equal the total of every other segment.
  • Two segments of equal length must sum equally, and combined with the uniqueness of each region that is a strong deduction.
  • These lines reward arithmetic. Establish the shared total first, and only then the individual digits.

The rule, drawn

What does Region Sum Lines look like?

  1. Region Sum Lines rule illustration, step 1 of 3
  2. Region Sum Lines rule illustration, step 2 of 3
  3. Region Sum Lines rule illustration, step 3 of 3

Start with a single square

Where can you play Region Sum Lines?

Region Sum Lines is one of the 17 variants in Cryptic, each with a lesson and unlimited puzzles.

Get it onGoogle PlayPlay on the web