The math I use in secret isn't exactly in "secret" so to speak. My family often plays board games where you build out your specific little area or section of the game and then calculate all the points at the end. The addition/multiplication just comes so quickly to my head that I end up knowing who has won the game before we actually tally all the points. My dad yells at me to stop telling us the scores before we get the chance to add them up, but I just end up blurting it out, revealing who the winner is.

Time calculations is also a big part of the math I do "secretly". During long cross country runs i will time mile by mile and deduce how far we have gone and how far we have to go. It's not the best habit to get into, but it gives me something to do while I run. I also am constantly making myself timed schedules of the things I will do in a given day, how much free time I will have after them and what I can do to speed things up.

I hope to be able to figure these sorts of things faster and faster as the years go by!