Math Mammoth Add & Subtract 2-A deals with various addition and subtraction topics and word problems in the 2nd grade level, especially focusing on the basic addition and subtraction facts of single-digit numbers with an answer between 10 and 18. The goal is to memorize the facts, or at least become so fluent with them that an outsider cannot tell if the child remembers the answer or uses some mental math strategy to get the answer. Some children will accomplish this quicker and need less practice, whereas others will take longer. Thus, don’t assign all the exercises in the book by default. Use your judgment. You can also use games to reinforce the facts (various games are provided in the introduction of the book). The first few lessons in the book deal with some addition and subtraction strategies from first grade plus skip-counting in a 100-chart. The lesson Fact Families reviews the connection between addition and subtraction, and explains a strategy for missing subtrahend problems (such as ___ − 5 = 4). Then we go on to ordinal numbers, even and odd numbers, and doubling and halving. After that, we review how to complete the next whole ten. An example of this concept is the question: What number do you add to 23 to get 30? As an equation, we write: 23 + __ = 30. The next lesson goes a step further, as we study sums that go over ten, doing these sums in two parts. The next lessons provide lots of practice for learning and memorizing the basic addition facts. There are 20 such facts: from 9 + 2 till 9 + 9: 8 facts from 8 + 3 till 8 + 8: 6 facts from 7 + 4 till 7 + 7: 4 facts from 6 + 5 till 6 + 6: 2 facts The last part of the book includes various lessons titled Number Rainbows and Fact Families with.... These give lots of practice and reinforcement for the basic addition and subtraction facts, emphasizing the connection between addition and subtraction as a strategy for subtraction facts. This is the 2026 edition. The answers are appended.