by David Bodycombe
From New Scientist #3250, 5th October 2019
I’m on holiday in the lovely country of Philitaly, and planning to send plenty of postcards because postage is very cheap. But the country only allows up to three stamps on any letter.
Can you tell me which three denominations of stamps would allow me me to cover any cost of postage from 1 cent to 15 cents inclusive?
And which four stamp denominations would allow all values from 1 to 24 cents?