How to solve faster
Practical habits that cut minutes off your times: scan in a fixed order, delay full notes, follow chains of placements and avoid costly mistakes.
What it is
Speed in sudoku does not come from rushing. It comes from good habits that waste less time: looking in the right places, avoiding mistakes, and not doing work you do not need. This guide collects the habits that make the biggest difference.
If you play the daily puzzle on sudoku.ie, your time goes on the leaderboard. These tips will help you climb it, but enjoy the puzzle first. A calm solve is usually a faster one.
Habit 1: scan before you note
Writing full pencil marks takes time. On Easy and many Medium puzzles, you can place a large share of the grid by scanning alone. Start every puzzle with a scan, and only switch to notes when scanning runs out.
Habit 2: scan in a fixed order
Do not let your eyes wander. A good routine is to take the digits 1 to 9 in turn, and for each digit, cross-hatch every box that is missing it. A fixed order means you do not check the same thing twice or skip something.
Some fast solvers prefer to start with the digit that is placed most often. That works well too. The important thing is to have a routine and stick to it.
Habit 3: follow the chain
Each placement changes the cells around it. After you place a digit, check its row, column and box straight away. Very often the next move is right beside the last one. Following these chains is much faster than starting a fresh scan each time.
A worked example
You place a 6 at row 4, column 2. Instead of going back to your routine, you look around it.
- In box 4, the 6 was the second-last gap. The last empty cell, row 6, column 3, must be whatever digit box 4 is still missing. That is a 1.
- Now row 6 has a new 1. Box 6 was missing a 1, and the only cells left for it were in rows 5 and 6. With row 6 ruled out, the 1 goes in row 5. Checking the columns leaves just row 5, column 9.
Three placements in a few seconds, all from following the chain.
Habit 4: use light notes
When you do start notes, try only marking digits that can go in two places within a box. These are quick to write and often enough to finish a Medium. Fill in full notes only on Hard and Expert puzzles, or when light notes stop helping.
Habit 5: avoid mistakes
Nothing loses time like a mistake. Undoing ten moves or restarting a grid costs far more than the few seconds you save by rushing. Before you place any digit, take a moment to check its row, column and box. Accuracy is speed.
Habit 6: learn the techniques well
A technique you have to think about is slow. A technique you recognise at a glance is fast. Practise the patterns one at a time: pointing and claiming first, then naked pairs. Once they become automatic, your Medium times will drop a lot.
Habit 7: use the controls well
On sudoku.ie, the digit counts show how many of each digit are left to place. A digit with only one or two left to place is a quick win: check where it can go. Learn to switch in and out of notes mode without thinking.
A common mistake
The most common mistake is trying to go fast by guessing. Guessing feels quick, but a wrong guess can cost you the whole puzzle. The fastest solvers almost never guess. They just see the next logical move sooner.
When you will need it
Whenever you want to. Speed matters most on Easy and Medium days, where the logic is simple and good habits make the difference. On Hard and Expert days, accuracy and knowing your techniques count for more than quick hands. Typical times on sudoku.ie are 5 to 15 minutes for Easy, 10 to 25 for Medium, 20 to 45 for Hard, and 30 minutes or more for Expert.