Is it normal that i always have the urge to group things in twos, fours or 8's?

Well, ever since I was young I've had a huge urge to group loads of stuff in twos, fours and eights. I don't know why. I feel kinda uncomfortable if they're in other groups.

For example, when I'm going up the stairs in my home I always miss one stair and start counting them because I know there's 13 stairs in my house, but if I miss one then there will be 12, which is 8 + 4 and it makes me happier. Actually, I count every set of stairs I go up to see if they have a nice amount of stairs and if they don't, the next time I go up them I make sure to make it so they do, so if there were fifteen stairs I would mentally add one before going up them and counting them again to make 16 which is a really nice number because it's 4 * 4.

Even when eating cereal I count how many pieces of that cereal is on my spoon (unless it's really tiny like coco pops or Cheerios) and if it isn't a nice number like 2 or 4 or 8 I get rid of some of the cereal and try again.

I mean I even wrote four tags for this post because four. Is it normal? I don't even know...