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

factor out 10^7: 10^7(10²+10+1)=111*10^7
write 10^7 into (2*5)^7:               =111*5^7^2^7
                                                    =555*5^6*2^7

yes, 10^9+10^8+10^7 is divisible by 555