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Published online by Cambridge University Press: 22 September 2016
Collecting the free picture-cards in packets of cigarettes or tea has always been popular. The equivalent up-to-date example is the gift of a picture—card of a football team with each purchase of petrol. Many a parent has been asked the question ‘how soon will we get the set’. Let us state a fairly general problem based upon this idea of collecting a set. Our problem states: