This is 5.5. He is a smaller version of 55, since he is divided by 10. He probably looks a little bit weird because he doesn't have a step squad mask, but he's not a step squad like 55 is, so this is what he looks like.
Credit to Numberblocks creators @WigglyKarrot19 came up with the idea of 5.5 being a smaller version of 55.
