Multiple choice general knowledge math & puzzles

A 34" x 34" 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 35 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. 136

  2. 133

  3. 132

  4. 130
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A Correct answer
Explanation

To count total nails on a square with 35 on each side, we must avoid double-counting corners. Each corner nail belongs to two sides, so total = 4 × 35 - 4 = 136. Simply multiplying 4 × 35 = 140 would count each corner twice.

AI explanation

Nails are placed evenly along each edge of the square, but the 4 corner nails are shared between two adjacent sides. With 35 nails per side, the total is 4 × 35 − 4 (subtracting the 4 corners counted twice) = 136. This is the standard way to count nails/points placed uniformly around a square's perimeter. 133, 132, and 130 don't correctly account for the shared corners.

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