What's the Big-O cost of the code?

Method 5 (Print Primes): This method prints out all prime numbers from 2 to N. The outer loop runs from 2 to N, and the inner loop (which is wrapped into a function called isPrime) checks whether a given number x is prime or not. The way to check whether a number x is prime or not is to loop from 2 to sqrt(N) and check if x is divisible by any integer in that range This is a very straightforward but not very efficient way to print all prime numbers from 2 to N (if you search Wikipedia, you will find a lot more efficient ways, but those are more complicated) The outer loop for (long i=2; i