what is the actual real-world application of prime numbers? Or is it just a math concept that’s neat to see and figure out but doesn’t have any actual use case?

Question

I read that they have some uses within online encryption, but to be honest I never really thought about why we learned them in school until this morning.

In: 20

Answer 1

I see people mentioning cryptography, but there is actually another use that nature came up with. Cicadas only come out every so many years (depending on which brood it is) and they do this to avoid running into each other and competing for resources. They can’t just coordinate one group on one set of years, and another on another set, so they each independently came out after a prime number of years to avoid competing with each other. 5 and 7 are common numbers of years, so they only come out at the same time every 35 years. There are also some that come out every 3 years, which prevents 9 years from being a cycle, because the 9 year cicadas would always have to compete with 3 year cicadas.