This is a fun math concept book. A new reindeer joins the school and it’s put their number at 13 so when the groups are told to pair there is always a remain-deer. The book rhymes well and gets it’s lesson across.  Kids will understand it and the play on words of remainder and remain – DEER. All in all, this was a fabulous math book that got the concept of prime numbers across in an excellent understandable way.