Objective: Students will multiply integers. October 13, 2009 Math 102 Objective: Students will multiply integers. Aim: What are the properties of multiplication and how do we determine the correct sign for the answer to a multiplication problem? NYS Mathematics Standards: 7.N.12 Prior Knowledge: Find each product: 8 x 3 = _____ 17 x 1 = _____ 6 x 9 = _____ 5 x 0 = _____

Mini-lesson: When you multiply integers, the numbers that you are multiplying are called factors. The answer is the product. To find the product, multiply the absolute values of the numbers and determine the correct sign of the answer: If the signs are the same, the answer is positive. 2 x 4 = 8 and -2 x (-4) = 8 If the signs are different, then the sign of the product is negative. -2 x 4 = -8 and 2 x (-4) = -8

Properties of Multiplication Property States that Example Zero Any number times 0 equals 0 -5 x 0 = 0 Identity Any number times 1 equals that number -5 x 1 = -5 Commutative The order in which the numbers are multiplied does not change the product -2 x 5 = 5 x (-2) Associative The product stays the same when you change the grouping of the numbers (2 x (-3)) x 3 = 2 x (-3 x 3)

-5 x (-2) = -10 ____________ -3 x 6 = -18 ____________ Guided Practice: State which of the following are correct or are not correct: -5 x (-2) = -10 ____________ -3 x 6 = -18 ____________ 8 x (-5) = -40 ____________ Simplify. Name the property. 5 x (-1) x 7 = 5 x 7 x (-1) ____________________ = 35 x (-1) ____________________ = ____

Independent Practice: Assessment: Homework: 8 – 4 “Homework Practice” worksheet