Let's get back to business, and in this chapter business means tasks. I don't want to spend all the time talking about the theory and classes and interfaces, so I will start by introducing some code. Actually, it is not my code—I got it from our good friend, Mr. Smith.

For the past few chapters, he was quite busy, working on things botanical, so I let him be. (He gave me a comprehensive overview of his activities, but I'm just a programmer, and I didn't really understand him.) Now he has more spare time, and he returned to his great love—prime numbers. He is no longer trying to improve SlowCode. Now he studies how the probability of finding a prime number changes when numbers become larger. To do so, he wrote two simple functions (shown as follows) that check a range of numbers and count how many prime numbers are in this range:

function IsPrime(value: integer): boolean;
var
  i: Integer;
begin
  Result := (value > 1);
  if Result then
    for i := 2 to Round(Sqrt(value)) do
    ...