Multiple choice general knowledge math & puzzles

You have a balance and the following items of which you know the weights: a small coin weighing 5g, a pen weighing 10g, an eraser weighing 20g, a holepunch weighing 40g, and a stapler weighing 80g. How many different possible weights can you measure with these items?

  1. 15

  2. 30

  3. 31

  4. 20
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The weights are 5, 10, 20, 40, 80. These are powers of 2 multiplied by 5. Any combination of these 5 items produces a unique sum (binary representation). There are 2^5 - 1 = 31 possible non-zero weights.

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