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Reversible hours (Posted on 2015-12-07) Difficulty: 3 of 5
Even upside down, a bat can continue to use its digital watch, because some hours are the same even when viewed in reverse. For example, this is what happens with 12:21.
Let's call these hours reversible.

What is the shortest interval between two reversible hours?

Source:Rudolpho Korchan.

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Colon included | Comment 1 of 4
The only times that can possibly have the colon in the right place even upside down must have 2 digit hours.  Therefore 10:01, 11:11, 12:21.  Each spaced 70 minutes apart.

On a 24 hour clock 15:51, 20:02, 21:12, 22:22 give a few more spacings of 70 minutes but none shorter.

  Posted by Jer on 2015-12-07 16:14:42
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