What is the greatest number of Friday the 13ths you can have in a year?
A: 3
It last happened in 2009 (Feb, Mar, Nov) and will happen again next year (Jan, Apr, Jul). Today is the only Friday the 13th this year.
You get one of these every time a month starts on a Sunday. What?
A: Friday the 13th
The next one is coming in May.

How many years until we get another Friday the 13th in the month of August?
A: 11 (2021)
The next Friday the 13th is in May 2011, followed by January 2012 (the first of 3 in 2012).