In two famous and popular puzzles a participant is required to compare two numbers of which she is shown only one. The first puzzle is known as the paradox of the double sum, the second, due to Cover is known as "which is the larger number". Although the puzzles have been discussed and explained...

In two famous and popular puzzles a participant is required to compare two numbers of which she is shown only one. In the first one there are two envelopes with money in them. The sum of money in one of the envelopes is twice as large as the other sum. An envelope is selected at random and...