Find a 13 digit positive integer N whose base ten representation consists entirely of 8s and 9s such that 2¹³ divides N.

(In reply to re: answers- spoiler by Charlie)

I was short of time to write down my "induction reasoning "and your presentation provided a faultless proof, thus complementing my layout.

My final answer was reached by adding 8 or 9 as a 1st digit followed by a previous result i.e. 8,88,888,9888  etc (thanks for correcting my typo -  I've edited my post ).

All said , it was a very nice problem!

 

Posted by Ady TZIDON on 2011-12-22 11:08:32