Thales measured the height of the inaccessible pyramid and the distance of the unreachable ship from the harbor, demonstrating that anything that can be plotted on a plane can be measured; Euclid, with the product of known prime numbers, continually generates new primes and demonstrated that prime numbers are infinite; Peano, with the second of his five axioms, affirmed that for every natural number there exists a successor number +1. We will never be able to claim to have developed Euclid's inaccessible primes or Peano's unattainable number, but twin primes are two of the infinite primes, one of which is a successor number +2 of the other prime, and the sum of the two primes is always a number 6n; by representing even numbers in the form 6n or 6n±2 and odd numbers in the form 6n±1 or 6n±2±1, we can demonstrate that Euclid's inaccessible primes and Peano's unattainable successor number exist. All prime numbers, all twin primes, all Mersenne primes which are the sum of numbers in double proportion and generate the even perfect numbers, all odd numbers 3n of the Collatz algorithm whose successor +1 is a power 2^n_even which when halved is 2^(n-1) and ends at 2^0 = 1 and all even numbers and all odd numbers which are the sum of 2 or 3 primes, all exist and, even if they will never be known, the final digit of the prime numbers and of the successor number which can be a prime or composite number is known.