3 Dice, 2 times

I know the odds of rolling an 11 or higher on 3 dice is 50%, but what are the odds of rolling an 11 or higher two times in a row?

I'd like to know how to do the math, because I have the same question about rolling a 10 (62.5%), 9, etc.

Thanks for any help!

Square the odds of an event happening once to get the odds of it happening twice... cube it to get the odds for three in a row... etc.