School-Safe Puzzle Games

Counting nails quickly

Thanks to www.syvum.com for this brain teaser:

A 33″ x 33″ 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 34 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?

Answer will follow in the comments section below in 1-2 days.

3 Comments to “Counting nails quickly”


  1. RLP | Profile

    Answer: 132 nails


  2. s | Guest

    i got 136 simply by multiplying the four sides by 34. how did u get 132? by subtracting the four for the sides because of the distance?


  3. ian | Guest

    count 1 corner but not the other so you count 33 nails on 1 side.
    33×4=132
    remember, you counted 4 corners and 4 sides if you remember. so you left out none but there are 34 on all sides.


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