Sudoku and Calcudoku are both grid-based logic puzzles you solve by pure deduction, so solvers naturally wonder how alike they really are. The short answer: Calcudoku is very close to Sudoku. Below we lay out what the two share, where they part ways, and whether the skills you have built on Sudoku will carry over.
- Grid: n×n (commonly 4×4-9×9)
- Closeness to Sudoku: Very Close
- Also called: KenKen, Mathdoku, Kendoku
What is Calcudoku?
A Latin-square grid divided into cages, each printed with a target and an operation the cage's numbers must produce. Here are the rules in full:
- Fill an n×n grid so each row and column holds 1-n exactly once.
- Cages carry a target and an operation (+, −, ×, ÷); the cage's numbers must produce that target.
- A number may repeat inside a cage, as long as it doesn't break the row/column rule.
See a Calcudoku cage
Calcudoku (also sold as KenKen) is a Latin square split into cages, each printed with a target and an operation. Here a two-cell cage marked "6×" holds 2 and 3, since 2 × 3 = 6.
A Calcudoku board: each coloured cage carries a target and an operation. Fill 1-4 in every row and column so each cage's digits hit its target - a "6×" cage, for instance, holds 2 and 3.
Swap the boxes for arithmetic cages and you have Killer Sudoku with all four operations - very close to Killer Sudoku Pro. The Latin-square rule is Sudoku's core, and the "which digits make this target?" reasoning is exactly Killer's combination logic, extended from sums to products and quotients.
What Calcudoku shares with Sudoku
- The Latin-square rule - each number once per row and column - is Sudoku's core.
- Cages with arithmetic targets are the idea behind Killer and XV Sudoku.
- Combination analysis - listing which numbers hit a target - drives both.
How Calcudoku differs from Sudoku
- It uses subtraction, multiplication and division, not just addition.
- A number can repeat within a cage, which Killer cages forbid.
- There are no boxes, and the grid is often smaller than 9×9.
Do Sudoku skills transfer?
The cage-combination skill from Killer Sudoku transfers directly - you just extend it from sums to products and quotients. A "×12 in two cells" cage is the same kind of "which pairs make this?" reasoning as a Killer sum.
Brush up on the technique that carries over: Killer Sudoku Combinations.
The verdict
Calcudoku (KenKen) is Killer Sudoku with the full four operations and no boxes - arithmetic cages on a Latin square.
Prefer to stay with Sudoku?
If Calcudoku appeals, these Sudoku variants scratch the same itch and you can read up on each here:
Where to play it
If it was Sudoku you came for, the level is the choice that matters more than the variant - Calcudoku and Sudoku part ways on the rules, but a Sudoku grid can be a two-minute warm-up or an hour of work depending on nothing but how much of it you are given.
Difficulty and type are two separate dials here: the type sets the extra rule, the level sets how much of the grid you start with. Easy Sudoku leaves 36 of the 81 cells filled, so there is always an obvious next move somewhere; Evil Sudoku leaves 23, with no easy moves at all. Take it at the gentler end while the pattern is still new, and move up once it stops being a fight.