Pick a number — say, 1. Find every row and column that already has a 1. Those rows and columns can't have another 1, so cross them out. Whatever box still needs a 1, only the uncrossed cells can receive it. If only one cell is uncrossed in a box, place the 1 there. Then move to 2, then 3, all the way to 9. Beginners often go 1–9 in order; experienced players start with whichever number already appears most on the board, since it has the fewest open spots.

Look at one empty cell. Check its row, column, and 3×3 box — every number already placed there is eliminated as a candidate. If only one number from 1–9 isn't eliminated, that's the answer. Place it immediately — no guessing involved. This is the most common technique in Easy puzzles.

Instead of asking "what fits in this cell?" ask "where can the number 7 go in this row?" Scan every empty cell in the row — if only one of them can accept a 7 (because all the others already have 7 in their column or box), then that cell must be 7. This feels less intuitive than Naked Single but unlocks many more placements once you get it.

Use ✏️ Auto-fill to see pencil marks. If two cells in the same row, column, or box both show only "4, 7" as candidates — those two cells must contain 4 and 7 (in some order). You don't know which yet, but you know no other cell in that unit can have a 4 or 7. Eliminate 4 and 7 from all other cells in the unit. This often creates new Naked Singles.

Look at a box and pick a number that still needs to be placed there. If all the cells that could contain that number are in the same row (or column), then that number must go somewhere in that row within this box. That means the same number can't appear anywhere else in that row outside the box — eliminate it from those cells. Think of it as the box "pointing" a number in a specific direction.

Look at a row. If a particular number can only go in cells that all belong to the same box, then that number must go somewhere in that box within this row. So it can't go anywhere else in that box — eliminate it from all other cells in the box that aren't on this row. This is Pointing Pair viewed from the row's perspective instead of the box's perspective.

Imagine the number 5 can only go in two cells in Row 2 (say columns 3 and 7), and also only in two cells in Row 8 (same columns 3 and 7). These four cells form a rectangle — an "X-Wing." Regardless of which diagonal of the X holds the 5s, columns 3 and 7 are covered. So you can safely eliminate 5 from every other cell in columns 3 and 7. This is a powerful technique that feels like magic the first time it clicks.