Numbers

I LOVE numbers!  If only everything in life could be solved using logical mathematical calculations.  LOL! 

Here's a little number puzzle for you:
What do these have in common?

1331
33
-11
1/11



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*Think of the date.



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11*11*11
11+11+11
11-11-11
11/11/11

I love fun dates like this. :)  Happy 11-11-11