Most beginners approach a fresh Sudoku grid the same way: eyes darting around the puzzle, looking for any number that might reveal itself. It feels natural — scan everything, grab what you can, fill as you go. The trouble is that random scanning means you check some areas three times and others not at all. The fix is simple: pick a fixed starting point and work the grid in order. The top-left corner is a good default. But it's worth being clear about why, because there's a popular myth about corners that doesn't hold up.

The Myth: Corners Are Easier

You'll sometimes hear that corner boxes are “less constrained” or that they give up digits faster than the middle. They don't. Every 3×3 box in a Sudoku, corner or centre, shares its three rows with two other boxes and its three columns with two more — four neighbouring boxes in total, every time. The top-left box and the centre box face exactly the same amount of outside pressure. Nothing about a corner's position makes it easier to solve.

What actually makes a box easy is how many digits are already in it and in the boxes around it. And that changes from puzzle to puzzle. Take two from our own library: in Easy Sudoku #1, the top-left box starts with only 3 givens while the boxes next to it have 5 and 6. In Hard Sudoku #1, the top-left corner has 5 givens and the top-right corner has just 2. Same position on the grid, completely different starting points.

So Why Start in a Corner at All?

Because a corner is a fixed place to begin a systematic sweep. The value isn't the corner — it's the habit of working the grid in the same order every time, so nothing gets skipped. Start top-left, work that box, move right, then drop down a row of boxes, the same way you'd read a page. When you get to the end, go around again. Every box gets looked at, every pass.

The Better Rule: Start With the Fullest Box

If you want the fastest possible start, do one quick thing before your sweep: count the givens in each box and begin with the fullest one. A box with 6 or 7 digits already in it has only 2 or 3 empty cells, and the missing digits are often forced by the rows and columns running through it. That's where your first placements come from — whether it's a corner, an edge or the centre.

The Technique: Box Scanning

Whichever box you start with, the method is the same. For each digit 1 through 9 that's missing from the box, look along the three rows and three columns that pass through it. If a digit already appears in two of those three rows, it can only go in the remaining row. Then check the columns: any cell in that row whose column already contains the digit is ruled out. Often that leaves exactly one cell. Place it, move to the next missing digit, and when the box is done, move on.

Every digit you place adds pressure to the boxes that share its row and column, which is why the second and third boxes you work usually go faster than the first. On an easy puzzle, this sweep alone will solve the whole grid. On harder puzzles it gets you the first dozen or so digits before you need pencil marks and the more advanced techniques.

Try It

Open Easy Sudoku #1 and count the givens in each of the nine boxes before you place anything. Start with the fullest box, box-scan it, then sweep the rest of the grid in reading order. It's a small change, but it turns a random scramble into a method — and a method is what carries you into the harder puzzles.