Compare Techniques
Struggling to tell similar techniques apart? Select two or more techniques to see their differences side by side — difficulty, prerequisites, when to use each one, and more.
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| Property | Naked Singles | Hidden Singles |
|---|---|---|
| Difficulty | beginner | beginner |
| Lesson # | 6 | 7 |
| Rating | ★★★★★ | ★★★★★ |
| The Idea | Imagine you are at a dinner table and each seat has a name card. After everyone else sits down, the constraints from every direction leave only one name for your seat — no guessing needed. | Imagine assigning lockers to students. Even though a particular locker could fit several students, if one student has no other locker available, that student must get this one — regardless of who else could have used it. |
| When to Use | After pencil marking an area, look for any cell whose candidate list has been reduced to a single digit. That cell can be solved immediately. | After scanning for Naked Singles, switch your perspective: instead of asking which digit fits a cell, ask where a specific digit can go within a row, column, or box. If a digit has only one legal cell in any unit, place it there. |
| Steps | 7 steps | 7 steps |
| Prerequisites | Pencil Marking | Pencil Marking |