By Susan Denham I ONCE had a job in a department store, working in the House Name Department. For example, I had to make “Dunromin” (taking 8 letters) and “Four hundred and twenty-one” (taking 23 letters). On one occasion a customer ordered his three-figure house number spelt out in this way. I prepared the invoice and wrote on it (in figures) the number of letters used. But the invoice clerk thought this referred to the house number so he replaced it (in figures) with the number of letters that house number would take. His superior again thought the number referred to the house number so he replaced it (in figures) with the number of letters that house number would take. The auditor again thought the number referred to the house number so he replaced it (in figures) with the number of letters that house number would take. He then prepared the bill accordingly. The customer turned out to be very lucky: at each stage in this long process the number had been reduced and the bill was for less than half what the Es alone would have cost. How many letters should the customer have been charged for? A £10 book token will be awarded to the sender of the first correct answer opened on Thursday 6 April. The Editor’s decision is final. Please send entries to Enigma 812, New Scientist, King’s Reach Tower, Stamford Street, London SE99 0BB. The winner of Enigma 806 was Richard Jones of Nottingham. Answer to Enigma 806 Arrow route 1, 4, 5, 6, 14,