Sunday Times Teaser 2562 – Chez Nous
Published: 30 October 2011 (link)
A sign-writer stocks signs of house numbers written in words, from “one” up to my own house number. The signs are kept in boxes according to the number of letters used. Eg, all copies of “seven” and “fifty” are in the same box. Each box contains at least two different signs. Boxes are labelled showing the number of letters used, eg the box holding “fifty” is labelled “five”. Naturally, the sign-writer has used signs from his own stock for the labels. To label all the boxes he needed to take signs from half of the boxes.
What is my house number?