Here are books that can be used for reinforcing math concepts with young children: 26 Letters and 99 Cents by Tana Hoban What Comes in 2's, 3's, and 4's? by Suzanne Aker Alexander, Who Used to be Rich Last Saturday by Judith Viorst The Doorbell Rang by Pat Hutchins 10 Apples up on Top by Theo. LeSieg 10 Black Dots by Donald Crews 10 in a Bed by Mary Rees Seven Little Rabbits by John Becker Inch by Inch by Leo Lionni