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Wilson's theorem
With Wilson's theorem, you can determine if a number is prime.
Explanation
If you can divide (p − 1)! + 1 by p, the number p is prime. The formula reads
When calculating factorials there emerge very large numbers quickly, so the formula is not very usefull.
Examples
The number 7 is prime, because
The number 4 is not prime, because
The number 2 is prime, because
HistoryThe British mathematician John Wilson rediscovered this theorem of the Arab astronomer Alhazen in 1770. |