Finding a prime number after a given number

Question

How can I find the least prime number greater than a given number? For example, given 4, I need 5; given 7, I need 11.

I would like to know some ideas on best algor

Answer 1

I generally see two ways to do that.

• counting up from n and checking every number for it being prime or not
• generate prime numbers and check against them. (maybe do that beforehand, use an existing primenumber table, so you don't need to calculate stuff everytime (well as long as N is within the range of your pre-calculated table)

maybe this helps too, (simply replace 2 with your given Number and N with infinite :D ) finding all prime numbers between 2 and N