I have a question that is very important to me related to the book *Basic Statistics for Business and Economics* for organizing data into a frequency distribution:

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> Step 1: Decide on the number of classes. The goal is to use just enough groupings or classes to reveal the shape of the distribution. Some judgment is needed here. A useful recipe to determine the number of classes ($k$) is the "2 to the $k$ rule". This guide suggests you select the smallest number ($k$) for the number of classes such that $2^k$ is greater than the number of observations ($n$): [$n \le 2^k$​]
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I want to know, how can I prove this formula?