As I said, checking for each and everyprime is not a good idea when you write such functions, instead you should check the logic and to me it seems perfect (well, within excel's limitations of handling arrays and large numbers) I think there must be a mistake in the formula you have specified. Shuffle a list of values in excel using random numbersД¬orrect way to simulate dice throws in excel More random stuff on randomness and numbers If so, the number is вЂњnot primeвЂќ, else, it is a вЂњprime numberвЂќ. It just calculates the minimum of all reminders when the number x is divided by values between 2 and sqrt(x) and sees if it is zero. Hit ctrl+shift+enter and bingo, it tells you if the number is prime or not. (assuming the number is in the cell B5) type the below formula and And that brings us to an interesting array formula trick to check if a number is prime or not. But when I get a chance to poke with randomness or numbers, I always lap it up with joy. I never really became the math-geek I always wanted to, instead I became an insurance expert with tons of passion for data and visualization. During my 3rd year of graduation I went and purchased the volume 2 of Donald KnuthвЂs Art of Computer Programming and thus began my love with all things random and prime. I am math-geek-wannabe, if there ever is such a category.

List of prime numbers .xls