The puzzle a 12 x 12 grid made up of 3 x 4 subgrids (called "regions").
Each number in the solution therefore occurs only once in each of three "directions", hence the "single numbers" implied by the puzzle\'s name..
The goal is to fill in the empty cells, one number in each, so that each column, row, and region contains the numbers 1 through 12 exactly once.
Some cells already contain numbers, known as "givens".
The puzzle a 12 x 12 grid made up of 3 x 4 subgrids (called "regions")