def isPrime(n):
  if n<2:        #1, 0 and all negative numbers are not prime
    return False
  elif n==2:    #2 is prime but cannot be calculated with the formula below becuase of the range function
    return True
  else:
    for i in range(2, n):
      if (n % i) == 0:    #if you can precisely divide a number by another number, it is not prime
        return False
    return True            #if the progam dont return False and arrives here, it means it has checked all the numebrs smaller than n and nono of them divides n. So n is prime