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# Blue Series

Usually printed in 3 - 5 business days
Math Mammoth Add & Subtract 2-B is a continuation to the book Math Mammoth Add & Subtract 2-A. The goal of this book is to study addition and subtraction within 0-100, both mentally and in columns, especially concentrating on regrouping in addition (carrying) and in subtraction (borrowing). Mental math is important because it builds number sense. This book includes many lessons that practice mental math. For example, the child practices adding and subtracting two-digit numbers when one of the numbers is a whole ten (such as 30 + 14 or 66 − 20). Children also learn to solve sums such as 36 + 8 or 45 + 9 with mental math (where there is a regrouping). We compare these to the sums 6 + 8 and 5 + 9. The child knows that 6 + 8 fills the first ten and is four more than the next ten. The child will then learn to use that fact when adding 36 + 8. The sum 36 + 8 fills the next whole ten (40), and is four more than that, or 44. Simultaneously with this, the student learns how to add two-digit numbers in columns with regrouping, which is explained in detail with the help of visual models (base-ten blocks). You are welcome to use the actual physical manipulatives to get the idea across, if you prefer. The main concept to understand is that 10 ones are regrouped to form a new ten, and this new ten is written using a little “1” in the tens column. The next lessons teach column subtraction, initially without regrouping. The following lessons then practice in detail the process of regrouping (aka borrowing). First, the lesson Regrouping practices breaking down a ten into 10 ones when we cannot subtract from the ones. It is crucial that the child understands what happens here. Otherwise, the child might end up only memorizing the procedure, and will probably at some point misremember how it was done. If you notice that the child does not understand the concept of regrouping, provide more practice with concrete manipulatives or visual exercises before proceeding. After learning regrouping, we practice mental subtraction in two separate lessons. One of them expounds on several methods for mental subtracting. Another is about Euclid's game—a fun game that also practices subtraction of two-digit numbers.

### Details

Publication Date
Feb 9, 2007
Language
English
Category
Education & Language
Contributors
By (author): Maria Miller

### Specifications

Pages
95
Binding
Paperback
Interior Color
Color
Dimensions
US Letter (8.5 x 11 in / 216 x 279 mm)