Python: Sieve of Eratosthenes method, for computing prime number - w3resource

Python program to find a number is prime or composite

SOLVED: Write a Python function isPrime(number) that determines if the integer argument number is prime or not. The function will return a boolean True or False. Next, write a function HowManyPrimes(P) that takes an integer P as an argument and returns the number of prime numbers whose value is less than P. And then write a function HighestPrime(K) that takes integer K as an argument and returns the highest prime that is less than or equal to K.