Cell first means you tap a cell, then choose the digit. Number first means you choose a digit, then tap every cell it belongs in. Cell first matches how you think when you look at one cell and work out its answer. Number first matches how you think when you scan the grid for one digit at a time. Neither is better in general. The right one depends on the step you are on, which is why the best setup is an app that lets you use both without digging through settings.
Cell first, step by step
- Tap the empty cell you have solved.
- Tap the digit on the keypad.
- Move to the next cell and repeat.
Every placement costs two actions, and your eyes jump from the grid to the keypad and back each time. On a phone that keypad usually sits below the board, so your thumb makes the same round trip.
Cell first shines when you are solving by cell. You find a naked single (a cell where only one digit fits), you place it, and the next deduction is somewhere else with a different digit. Each placement is independent, so there is nothing to gain from keeping a digit selected.
Number first, step by step
- Select a digit on the keypad. It stays selected.
- Tap each empty cell where that digit goes.
- Select the next digit, or turn the current one off.
Placing the same digit in four cells costs five actions instead of eight. The bigger gain is mental: you stay focused on one digit while you scan its rows, columns and boxes. This is exactly how hidden singles are found, so number first fits the opening of most puzzles, when you sweep 1 through 9 and fill in the obvious spots.
Its weak spot is the mid-game. When each deduction produces a different digit, you switch the selected digit every time, and number first turns into cell first with an extra tap. The other risk is forgetting a digit is still selected and tapping a cell by habit.
Side by side
| Cell first | Number first | |
|---|---|---|
| Actions per placement | 2 | 1, plus 1 per digit switch |
| Best phase of the puzzle | Mid and late game, scattered deductions | Opening sweeps, finishing off a digit |
| Matches this way of thinking | What goes in this cell? | Where does this digit go? |
| Pairs well with | Naked singles, notes on one cell | Hidden singles, notes across many cells |
| Common slip | Tapping a neighbour key on a small keypad | Leaving a digit selected by accident |
What about notes?
The same split applies to pencil marks. Cell first is natural when you write all the candidates for one cell. Number first is natural when you mark every spot a single digit could go in one box, which is the core of Snyder notation. If you use notes a lot, the ability to switch between the two matters even more.
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Download Sudoku Royale: Free on iOSHow Sudoku Royale handles both
Sudoku Royale has no input mode setting. Both orders are always available, and the one you use is decided by where you touch.
Cell first on the board
Tap an empty cell and a picker appears over the board, with each digit placed over the 3x3 box of the same number: 1 top left, 5 in the middle, 9 bottom right. Tap the digit. The targets are the size of a whole box, much bigger than keypad keys, so near-misses are rare.
You can also do it in one motion: press the cell, slide into the box of the digit you want, and release. That collapses cell first into a single gesture. See slide to select for how it feels once the positions are memorised.
Number first on the number keys
The row of 1 to 9 keys below the board is the number-first side.
- Tap a key and the digit stays selected. Each empty cell you tap gets it. Tap the key again to turn it off.
- Hold a key and the digit is selected only while your finger is down. Let go and nothing is left switched on, which removes the stuck-digit slip.
- Slide along the keys while holding, and the board lights up every cell holding that digit as you pass over it. It is a quick way to see which digits are nearly done.
- Drag across cells with Notes on and a digit selected to write that note into each cell you pass.
The picker and the number keys are never on screen at once. Selecting a key closes an open picker, and the keys fade while the picker is up, so you always know which mode you are in. A digit whose nine copies are all placed dims on its key.
A practical way to combine them
- Opening: number first. Hold 1, tap every cell where it is forced, move to 2, and so on through 9.
- Middle: cell first. Deductions come from different digits in different places, so tap or slide on the board.
- Notes phase: number first with Notes on, dragging one candidate across the cells of a box.
- Finish: whichever is closer. When one digit is left in several spots, number first. When the last cells are all different, cell first.
If you want to try both on the same puzzle, an Easy puzzle in Practice is the place. There is no time limit, and mistakes cost nothing. For more on raw entry speed, including keyboards on the web, read sudoku input methods compared.
Frequently Asked Questions
What is the difference between number first and cell first in sudoku?
Cell first means selecting a cell and then choosing its digit. Number first means selecting a digit and then tapping every cell where it goes. Cell first suits scattered deductions; number first suits scanning for one digit at a time.
Which sudoku input method is faster?
Number first is faster when you place the same digit several times in a row, because the digit stays selected. Cell first is faster when every placement is a different digit. Using both, depending on the phase of the puzzle, beats sticking to one.
Does Sudoku Royale have number-first input?
Yes. Tap a key in the row of 1 to 9 under the board and the digit stays selected; each empty cell you tap gets it. Hold the key instead and the digit is only selected while your finger is down. Cell-first input works at the same time by tapping or sliding on the board.
Do I need to change a setting to switch input modes?
Not in Sudoku Royale. Touch the board for cell first, touch the number keys for number first. Some other apps put number first behind a settings toggle.