Use each of four numbers once to make 24. Tap a number, an operation, then another number.
Today's numbers are 5, 5, 5, 6. Make 24 using each exactly once — pencil and paper work fine.
Square any number ending in 5 in your head, with no working, using one multiplication you already know.
Every game, and how long each one takes.
Nothing expires. Yesterday's is still there.