Two Irrational Numbers from the Last Nonzero Digits of $n!$ and $n^n$

by Gregory Dresden

Mathematics Magazine
October, 2001

Subject classification(s): Algebra and Number Theory | Number Theory | Irrational Numbers
Applicable Course(s): 4.3 Number Theory

The author considers two infinite decimals, where the $n$th digit is the last non-zero digit of $n!$, creating the number $F$, and using $n^n$, creating the number $P$. The author shows that both $F$ and $P$ are irrational.

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