primeNum = [] # list for storing prime numbers having 3 digits and starting with 5
for i in range(500,600):
    for j in range(2,i): # inner loop goes from 2 to i
        flag = False # flag initialized False for every iteration
        if i%j == 0:
            flag = True  # if remaining from i divided by any j equals to zero set flag to True 
            break # break the loop
    if flag==0: # if flag equals to False i is prime number
        primeNum.append(i)