import random

def generate_random_number_string(length=10):
    numbers = ''.join(random.choice('0123456789') for _ in range(length))
    # Insert dashes every 4 digits
    formatted_string = '_'.join(numbers[i:i+4] for i in range(0, length, 4))
    final_seller_string = f"BUYER3_{formatted_string}"
    return final_seller_string

# Generate and print the random number string
#i = 0
#while i < 5:
#    print(generate_random_number_string())
#    i = i +1