This is so quick and easy to set up! Simply make some play dough (recipe on my Pinterest page here), use some different coloured chalk pens to write differentiated questions on the tuff spot and away you go! Begin by making the whole number first with the play dough. Then smash a part of it to see the part that is left over!
This activity led to my room being full of hulk noises and a slightly messy carpet. However, it was all worth it for the learning that was going on!