Number of words: 165

Imagine you had a 20 volume Encyclopaedia on a shelf with each volume 2 inches thick (about 5 cm) and the cover an additional quarters of an inch think on each side (about 0.6 cm) and a worm is crawling from the first page of volume 1 to the to the last page of Volume 20. How long is that distance?

Some people answer 50 inches that is (20 volume × 2”=40”) plus 20 volume × 2 sides ×1/4” =10”)= 50 inches total.

Many people say 49.5 inches, since we said first page to last page and thus the first and last covers can be excluded.

But the correct answer, is actually 4 inches less. i.e. that is 45.5 inches. Page one of the first volume is on the right hand side of the volume and the last page of the Volume 20 is on the left hand side of the Volume!

Excerpted from ‘Thinking in new boxes’ by Alan Iny and Luc de Brabandere