def digital_to_hexidecimal(digital_number):  
    """
    Convert a digital number to its hexadecimal representation.
    
    Parameters:
    digital_number (int): The digital number to convert.
    
    Returns:
    str: The hexadecimal representation of the digital number.
    """
    if not isinstance(digital_number, int) or digital_number < 0:
        raise ValueError("Input must be a non-negative integer.")
    
    return hex(digital_number)[2:].upper()

# Example usage:
if __name__ == "__main__":  
    try:
        number = 1500  # Example digital number
        hex_representation = digital_to_hexidecimal(number)
        print(f"The hexadecimal representation of {number} is {hex_representation}")
    except ValueError as e:
        print(e)