# Applications of prime numbers

Why are prime numbers important in real life? What practical use are prime numbers?

Borek
Mentor
Ask periodical cidacas why they use prime numbers for the cycle length.

1 person
from Wikipedia:
Primes are used in several routines in information technology, such as public-key cryptography, which makes use of properties such as the difficulty of factoring large numbers into their prime factors. Prime numbers give rise to various generalizations in other mathematical domains, mainly algebra, such as prime elements and prime ideals.

http://en.wikipedia.org/wiki/Prime_number

1 person
Borek
Mentor
Prime numbers give rise to various generalizations in other mathematical domains, mainly algebra, such as prime elements and prime ideals.

Definitely a real life application.

Definitely a real life application.

Isn't math real life?

:-)

HallsofIvy
Homework Helper
Definitely a real life application.
For a mathematician it certainly is!

Ask periodical cidacas why they use prime numbers for the cycle length.

Interesting Borek. I had to investigate:

The fact that the surviving periodical cicadas have life cycles built on prime numbers may have conferred key survival advantages. A prime-numbered lifespan means that predators cannot match their own shorter life cycles to the availability of cicada prey. For instance, if the cicadas had even-numbered lifespans, a predator with a two-year life cycle could expect a cicada feast, and a subsequent population bump, every few generations, because all even numbers are divisible by two. As explained in 2001 by a trio of researchers from the University of Chile and the Max Planck Institute of Molecular Physiology in Germany, “a prey with a 12-year cycle will meet — every time it appears — properly synchronized predators appearing every 1, 2, 3, 4, 6 or 12 years, whereas a mutant with a 13-year period has the advantage of being subject to fewer predators.”

1 person
from Wikipedia:
Primes are used in several routines in information technology, such as public-key cryptography, which makes use of properties such as the difficulty of factoring large numbers into their prime factors.

Poor Hardy! He went to his grave proud of the uselessness of number theory.

Strange that a discipline studied for millennia suddenly became useful only a couple of decades ago.

Poor Hardy! He went to his grave proud of the uselessness of number theory. Strange that a discipline studied for millennia suddenly became useful only a couple of decades ago.

true, but primes also became important with the invention and the use of computers ...