Variant Sudoku

X-Sums Sudoku Explained in One Short Example

0:15 · X-sums · Variant Sudoku

A row with a clue of 10 shows the X-sums rule. The first digit is 3, so you add the first three cells, and 3 + 2 + 5 = 10 matches the clue.

Full lesson and practiceFind X-Sums puzzles

Transcript

  1. 0:02The first digit says how many cells to add. The clue is their total.
  2. 0:06The first digit is 3, so add the first three digits.
  3. 0:093 + 2 + 5 = 10, the clue.

The rule

In X-sums sudoku, a clue outside the grid looks along its row or column. The first digit you meet, X, tells you how many cells to add, and the clue is the sum of those X digits.

The first digit counts itself. A 3 at the front means you add the 3 and the next two digits.

Worth memorizing

  1. The first digit counts itself.

    A 3 at the front means add three digits including the 3.

  2. A clue of 1 means the first digit is 1.

Practice x-sums in the lesson

More rule videos

0:15Killer cagesKiller Sudoku Rules Explained in One Short Example0:18XVXV Sudoku Rules Explained in One Short Example0:18Kropki dotsKropki Sudoku Dots Explained in One Short Example0:15ThermometersThermo Sudoku Rules Explained in One Short Example0:18ArrowsArrow Sudoku Rules Explained in One Short Example0:18German whispersGerman Whispers Sudoku Explained in One Short Example0:15Renban linesRenban Lines Explained in One Short Example0:15PalindromesPalindrome Sudoku Lines Explained in One Short Example

All 24 rule videos