Speed quiz
True or false logic puzzle: 5 by 5, number 2
Every cell makes a statement about other cells. A true cell's statement holds; a false cell's statement really is false. Mark them all.
- Format
- Logic grid
- Items
- 25 cells
- Limit
- 13:00
- Level
- Hard
- Checked
- 2026.10.03
The rules as listed below.
- Grid
- 5 by 5, 25 cells to mark
- Time limit
- 13:00
- Checks
- 3
- Press a cell to cycle its mark: true, false, then blank again.
- Check the grid once every cell is marked. A check says how many are wrong, never which.
- Keyboard: arrow keys move between cells; T, F set a mark and Backspace clears it.
- Pause whenever you like (Esc). The board hides while the clock is stopped.
Mark every cell true or false. The grid appears when you start.
About this quiz
Pure logic, no knowledge needed. Each statement is true or false, and whether it is depends on the others. Start with a cell that cannot be what it claims and follow the consequences.
- There is exactly one consistent way to mark the grid, and it can be reached without guessing.
- A good way in: suppose a cell is true, follow what that forces, and look for a clash.
- Cells are named like chess squares: the letter is the column, the number is the row.
More quizzes like this
| No. | Quiz | Section | Format | Items | Added |
|---|---|---|---|---|---|
| 01 | True or false logic puzzle: 5 by 5 A 5 by 5 grid of 25 statements about each other. Mark every cell true or false: only one way of doing it holds together. Speed / Logic grid / 25 cells | Speed | Logic grid | 25 | 2026.10.03 |
| 02 | True or false logic puzzle: 4 by 4 A 4 by 4 grid of 16 statements about each other. Mark every cell true or false: only one way of doing it holds together. Speed / Logic grid / 16 cells | Speed | Logic grid | 16 | 2026.10.03 |
| 03 | True or false logic puzzle: 6 by 6 A 6 by 6 grid of 36 statements about each other. Mark every cell true or false: only one way of doing it holds together. Speed / Logic grid / 36 cells | Speed | Logic grid | 36 | 2026.10.03 |