Multiple choice general knowledge math & puzzles

A 26" x 26" square metal plate needs to be fixed by a carpenter on to a wooden board. The carpenter uses nails all along the edges of the square such that there are 27 nails on each side of the square. Each nail is at the same distance from the neighboring nails. How many nails does the carpenter use?

  1. 102

  2. 104

  3. 106

  4. 108
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B Correct answer
Explanation

This is a perimeter counting problem. With 27 nails on each side: 4 × 27 = 108. However, each corner nail is counted twice (once for each adjacent side), so we subtract the 4 corner nails: 108 - 4 = 104 nails total.

AI explanation

With 27 equally spaced nails per side including the two corner nails, each side has 27-1 = 26 gaps, and the four corners are shared between adjacent sides so they should only be counted once each. Total nails = 4 x (27-1) = 104, rather than simply 4 x 27 = 108, because that would double-count the four corner nails.

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