perplexus.info :: Just Math : 39 does it

39 does it (Posted on 2012-02-19)

Prove that within any 39 consecutive natural numbers there must exist at least one number with the sum of its digits divisible by 11.
Bonus: Can the bound (39) be lowered?

Submitted by Ady TZIDON

Rating: 5.0000 (4 votes)

Solution: (Hide)

The bound cannot be lowered.(read all comments!)

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
A simpler explanation	broll	2012-02-20 02:00:25
Proof	Math Man	2012-02-19 13:48:41
solution I think--based on computer exploration	Charlie	2012-02-19 12:49:08
computer exploration -- bonus only is shown	Charlie	2012-02-19 12:38:12

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