If 4 pencils are of diameter 7mm,and they are held together in a square by an elastic band find the length of the band.
The length of the elastic band can be calculated by finding the perimeter of the square formed by the 4 pencils.
Each side of the square will be equal to the sum of the diameter of two pencils, since they are held together side by side. Thus,
Side of square = 2 x diameter of pencil = 2 x 7mm = 14mm
Perimeter of square = 4 x side of square = 4 x 14mm = 56mm
Therefore, the length of the elastic band required to hold the 4 pencils together in a square is 56mm.