<p>Math 123 Fall 2009 Review topics for test 2</p><p> Addition, subtraction, multiplication and division algorithms. Why do they work? Be able to explain each step of the standard algorithms, like we discussed in class. For addition and subtraction, know how to explain the steps using blocks. For multiplication, know how the standard algorithm is related to the area model. For division, know how the standard model is related to division using blocks. Be able to justify a non-standard algorithm: you don’t need to know any other algorithms (except lattice!), but given an algorithm, you should be able to explain why it gives a correct answer. Know how the lattice algorithm for addition and multiplication works. o Problems 3.2: 1, 3, 4, 33, 35, 36; o 3.3: 1, 2, 3, 4, 7 (a and b only), 11, 17, 18, 22.</p><p> Mental math and estimation: be able to mentally add, subtract, multiply and divide, and explain your strategies. You do not need to know strategies by name. Be able to use estimation in word problems, like the ones you had for homework. o Problems 3.4: 1, 2, 4, 5, 6, 8, 10, 14, 15, 16, 22.</p><p> Integers: be able to use the chip model, number line model, and patterns to explain rules for operations with integers. In particular, be familiar with the contents of the packet we did in class. o Word problems: 8, 14, 37 from 4.1 and 5, 11, 12, 13, 34, 36, 49 from 4.2.</p>