Puzzle 1

A 30" x 30" square frame needs to be fixed onto a wooden board. A carpenter uses nails all along the edges of the square such that there are 31 nails on each side of the square. Each nail is at the same distance from the neighboring nails. How many nails will the carpenter use? Email your solution with your full name to mathatitc@gmail.com. All winners will be given a prize for their effort. Good luck!