Speed quiz
Powers of two
Start at 2 and double it, again and again, for 20 steps. Type each power in turn, digits only. Press Enter on a wrong number and the run is over.
- Format
- Type them all
- Items
- 20 answers
- Limit
- 3:00
- Level
- Hard
- Checked
- 2026.10.03
- Answers
- 20
- Time limit
- 3:00
- Order
- One at a time, no skipping
- Matching
- Case and accents ignored
- Minefield
- One wrong answer ends it
- Answer each item in turn; the next appears when you get it right.
- Press Enter to check a guess.
- Pause whenever you like (Esc). The board hides while the clock is stopped.
Type each power of two in turn, from 2 to the power 1 up to 2 to the power 20.
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About this quiz
Powers of two are what you get by doubling over and over. They sit behind computer memory sizes, binary numbers and the old story of rice on a chessboard.
- 2 to the power 10 is 1,024, the number of bytes in a kibibyte.
- 2 to the power 16 is 65,536, the number of values a 16 bit number can hold.
- 2 to the power 20 is 1,048,576, just over a million.
- The last digits of the powers of two cycle through 2, 4, 8 and 6.
More quizzes like this
| No. | Quiz | Section | Format | Items | Added |
|---|---|---|---|---|---|
| 01 | Anything but 7 Click every number from 1 to 70 that has nothing to do with 7: not a multiple of 7 and no 7 among its digits. 54 are safe. Speed / Click the grid / 54 to click | Speed | Click the grid | 54 | 2026.10.03 |
| 02 | Click only the primes Click every prime number from 1 to 100, and nothing else. There are 25 primes in the grid, and one wrong click ends the game. Speed / Click the grid / 25 to click | Speed | Click the grid | 25 | 2026.10.02 |
| 03 | Count down from 100 by sevens Start at 100 and keep taking away 7: type 93, 86, 79 and so on down to 2. Fourteen answers, one minute, and one wrong answer ends the run. Speed / Type them all / 14 answers | Speed | Type them all | 14 | 2026.10.03 |