Among the natural numbers below 100, there are 30 that have special properties. Jovan lists them here in a table.
However, Jovan made a mistake and one of these numbers needs to be replaced. Which number should be inserted in place of the incorrect number?
The number 75 must be replaced with the number 74. The numbers in the table are each a product of two prime numbers and are sorted by magnitude. 75 is a product of three prime numbers, so it does not match any other number.
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This puzzle was originally The scientific spectrum Reprinted with permission.
