# Function to check if a number is prime
def is_prime(num):
    if num < 2:
        return False
    for i in range(2, int(num ** 0.5) + 1):
        if num % i == 0:
            return False
    return True

# Main function to find prime numbers starting with 5 and having 3 digits
def find_prime_numbers():
    prime_numbers = []
    for num in range(500, 600):
        if str(num)[0] == '5' and is_prime(num):
            prime_numbers.append(num)
    return prime_numbers

# Test the function
prime_numbers = find_prime_numbers()
print("Prime numbers starting with 5 and having 3 digits:", prime_numbers)