(1) Find a test for divisibility by 111.
(2) Extending this, find a test for divisibility by any number consisting solely of 1's.
Please explain why your tests work.
(In reply to Divide and conquer (spoiler)
by Steve Herman)
Great solution, however I was hoping someone would come up with an elegantly simple method that can be done "in one's head", along the lines of the divisible by 3 and/or 9 that most of us know. I grew up in the era before PCs and calculators, and these rules were extremely useful, almost necessary, then.
Who's up to the challenge?
Posted by Kenny M
on 2013-12-15 10:09:52