Seth is thinking of a number between 20 and 30. The number is prime and not more than 2 away from a perfect square. What is the number?

1 Answer
Johnson Z.
Apr 12, 2016

#23#

Explanation:

Start by listing out the numbers between #20# and #30#.

#21,22,23,24,25,26,27,28,29#

Rule out the numbers that are not prime.

#23,29#

The only perfect square between #20# and #30# is #25#. Since you know that the number is not more than #2# from #25#, the number must be #23#. #29# can't be the number since it is #4# from #25#.

#color(green)(|bar(ul(color(white)(a/a)23color(white)(a/a)|)))#

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