Add the number of objects and type the answer. If you get it correct, the happy face will smile.
For example, if there are three blocks on the left and three on the right, and you type the number 6, the face will smile.
Press a purple number on the bottom of the page to change the most number of shapes that will appear on each side of the + sign.
Press 'Do it again' or the ENTER (or RETURN) key to try it again.