Sieve of Eratosthenes

Enter a value and press the "Submit" button. All of the multiples larger than the number will be shaded green. This process slowly uncovers the prime numbers. Notice that only the values 2, 3, 5, 7, 11, 13, 17 and 19 are needed to uncover all of the primes less than 400. Can you find the 78 prime numbers less than 400?
Enter the Divisor: