ABSTRACT
This is one of the most important of tools in helping children count, understand place value, hone their memory skills, learn number bonds, investigate percentages, and look at fractions. Children may arrive in our schools with very little concept of the structure of the number system. Number words may be chanted, but values not understood. Mental arithmetic cannot be learned, understood and used unless there is a mental image on which to hang ideas. Every time I think I have used the 100 square in just about every way I can think of, I learn about another.
