Problems from the 2012-13 School Year [Click the problem to enlarge.] Click the other Archive tabs for even more problems!
Which ring did neither Don nor Erika hit?
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The Deca Tree
A set of ten cards, each showing one of the digits from 0 to 9, is divided up between five envelopes so that there are two cards in each envelope. The sum of the cards inside it is written on each envelope. What numbers could be inside the 8 envelope?