Drums and maths - number sequences

I posted a couple of weeks ago about Dan and Joplin's drums and twos game and Dan took it further today with 10s, 5s and then 4s.
Basically you take it in turns to go up the number sequence - 5, 10, 15 etc banging the drum each time you give an answer. They got as far as 200 for 2s, 4s, 5s and 10s ! Joplin had to count on his fingers for the 4s but he took his time and then his face just lit up as he reached the answer and banged the drum! The physical aspect really emphases the answer and I really think it is helping Joplin's mathematical thinking. He loves it anyway and Dan is great at gently helping if needed and knowing when to wait for Joplin to work it out for himself.