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What do the numbers 11, 69, and 88 all have in common?

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Originally posted by DumDum81
What do the numbers 11, 69, and 88 all have in common?
they all look the same upside down or in a mirror.

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They are all numbers 😀

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Originally posted by chatterbox
they all look the same upside down or in a mirror.
upside down (as in rotated 180 degrees in the plane of the writing surface) is right, but not in a mirror, at least not 69, which will make the digits themselves look backwards (a reversed "9" looks remotely like the "@" )!

here is a slightly more dificult problem:
assuming we retain the present calendar, what will be the next time we see a year that reads the same if inverted (i'm talking as written, not as shown in a seven-element digital display)?

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3003?

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Originally posted by qwiksylver
3003?
oops! i need to clarify.
"inverted" as in "rotating 180 degrees in the plane of the writing surface" if you do that with 3003, you get something like "E00E".
the method you suggest rotates around a horizontal axis through the middle of each digit, but you have to leave the plane of the writing surface.
sorry for the confusion!

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Originally posted by BarefootChessPlayer
upside down (as in rotated 180 degrees in the plane of the writing surface) is right, but not in a mirror, at least not 69, which will make the digits themselves look backwards (a reversed "9" looks remotely like the "@" )!

here is a slightly more dificult problem:
assuming we retain the present calendar, what will be the next time ...[text shortened]... e if inverted (i'm talking as written, not as shown in a seven-element digital display)?
6009?

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Originally posted by iamatiger
6009?
yup!
can you figure out the rest of the four-digit ones?

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1001
1111
1691
1881
6119
9116
8118
6009
9006
6699
6969
6889
8008
8698
8968
8888
9006
9886
9696
And thats all I got off the top of my head

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