10 boards of varied difficulty. Each board has three standard form and each of the three's factored form functions with missing digits. Students use the ten digits 0 - 9 to correctly fill in the board. All digits are used on each board and there is one unique solution, even though some digits may fit in more than one spot. All digits are used each time and only once. The boards aid the student to understand the "why" of factoring as well as recalling their number sense, instead of just memorizing steps.