The 45 rule is a fundamental principle in Sudoku that helps solvers understand the mathematical relationships within the puzzle.
What is the 45 Rule?
Each row, column, and 3x3 box must contain the numbers 1-9, which sum to 45. This means the total of all numbers in any row, column, or box equals 45.
How to Use the 45 Rule
If you know the sum of some numbers in a row, column, or box, you can calculate what the remaining numbers must sum to.
Practical Applications
This rule is particularly useful in Killer Sudoku and other variants where sum constraints are given.