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What is Wilson's Theorem?

Published in Mathematics 2 mins read

A Fundamental Result in Number Theory

Wilson's Theorem is a remarkable result in number theory that establishes a relationship between prime numbers and factorials. It states that:

For any prime number p, (p - 1)! + 1 is divisible by p.

Understanding the Theorem

Let's break down the components of the theorem:

  • Prime Number (p): A prime number is a natural number greater than 1 that has only two divisors: 1 and itself. Examples include 2, 3, 5, 7, 11, and so on.
  • Factorial (n!): The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, 5! = 5 4 3 2 1 = 120.

Examples

Here are a few examples to illustrate Wilson's Theorem:

  • p = 2: (2 - 1)! + 1 = 1! + 1 = 2, which is divisible by 2.
  • p = 3: (3 - 1)! + 1 = 2! + 1 = 3, which is divisible by 3.
  • p = 5: (5 - 1)! + 1 = 4! + 1 = 24 + 1 = 25, which is divisible by 5.

Practical Insights

Wilson's Theorem has applications in various areas, including:

  • Primality Testing: Although not a practical method for large numbers, it can be used to determine if a number is prime.
  • Number Theory: It plays a role in proving other theorems related to prime numbers and factorials.

Conclusion

Wilson's Theorem offers a unique and elegant connection between prime numbers and factorials. It demonstrates that prime numbers possess a special property related to the factorial of one less than themselves. This theorem has implications in various areas of mathematics, particularly in number theory.

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