Help Help Help Help Help Help Help Help Help Prove the divisibility of the following numbers: 10^9+10^8+10^7 by 555

Pull out a common factor of 10⁷:

10⁹ + 10⁸ + 10⁷ = 10⁷ (10² + 10¹ + 10⁰)

… = 10⁷ × 111

Factorize 10 as 2 × 5, then distribute the power of 7:

… = 2⁷ × 5⁷ × 111

Pull out a factor of 5 and multiply it with 111:

… = 2⁷ × 5⁶ × 5 × 111

… = 2⁷ × 5⁶ × 555

So 555 divides 10⁹ + 10⁸ + 10⁷.