Twenty past

I have a talent, which consists of immediately forgetting things that are not important. Which is probably why I can read the same book several times, without being sure of how it ends. I have a hunch maybe, but I cannot be sure. This is the same talent which makes me never remember when the bus goes home. I'm in town, I know the bus is every 12 minutes and therefore I cannot be bothered to remember. However, now in December when it's friggin freezing I wish I had remembered. And the thing is I only have to remember 20 past, then I can calculate the rest. If it's 20 past, it'lll be 32, 44, 56 usw (und so weiter in German, meaning and so on in English). How difficult can it be?