What is euclid's theory about prime numbers?

Answer 1

That there are an infinite number of prime numbers.

Before we look an explanation or proof, we must agree on some points

1. The term number means whole number or integer

2. A Prime number is any number that has only 2 factors (1 and itself).

3. All numbers are either prime or the product of 1 or more primes; try and find a number that you cannot generate as the product of primes (e.g. 8 = 2x2x2; 36 = 2x2x3x3).

Now:

If you take any two or more prime numbers and find their product the resulting number will have the prime numbers used as factors. However, if you add 1 to the number then the prime numbers you used to produce this number will now no longer be factors of this new number.

Example

2,3,5 (first three prime numbers) 2x3x5 = 30

30 +1 =31 - now 2,3 and 5 are not factors as you will always have a remainder of 1 if you divide by any of the three original prime factors (2,3 or 5).

If you take all of the known prime numbers and find the product of all of these prime numbers we get a new number (call it Product of Primes or PP), PP will have all the know primes as its factors. If we now add one to PP (PP + 1=N) we will get a number, N, that will have none of the known primes as a factor. If we say that the highest value prime number known (that we used to generate PP) is Pi then N must either be prime or have a prime factor greater than Pi and thus Pi is not the highest prime number. Therefore there are an infinite number of prime numbers.