In this book, children progress to two-digit addition while learning the commutative property of addition- an important foundation for future math success. Problems incorporate both horizontal and vertical form addition, which prepares children for practice with three and four-digit addition. Upon completion, your child will be ready for advanced arithmetic! Topics Covered in this Book:-Horizontal addition review-Vertical form addition-Two-digit plus two-digit addition to 198-Early three- & four-digit addition-Addition of three two-digit numbers-Commutative property of addition-Patterns & sequencing 8 1/2 x 11 inches. paperback. 96 pages. full color.