Addition, Subtraction, Multiplication, and Division of Integers Lesson 11 Addition, Subtraction, Multiplication, and Division of Integers

Rules for Adding Integers When the signs are the same, keep the sign and add. When the signs are different, take the sign of the number with the higher absolute value and subtract.

Example 1 6 + (-14) + (-10) + 30 = Strategy: Follow the rules for adding integers. Step 1: Add the positive integers. 6 + 30 = 36 Step 2: Add the negative integers. (-14) + (-10) = (-24)

Step 3: Add the solutions from Steps 1 and 2. 36 + (-24) = 12

Solution The answer is 12.

Rules for Subtracting Integers Rewrite the subtraction problem as an addition problem: Change the minus to a plus. Change the sign of the number to be subtracted (the second number). If the second number is positive, make it negative; if the second number is negative, make it positive. Solve using the rules for addition.

Example 2 Subtract: 16 – (-13) = Strategy: Rewrite the problem as an addition problem. Step 1: Rewrite the problem. 16 + 13 = Step 2: Add. 16 + 13 = 29

Solution The answer is 29.

Rules for Multiplying Integers If the signs are alike, the answer is positive. If the signs are different, the answer is negative.

Example 3 (-25) x (-8) x (-2) = Strategy: Follow the rules for multiplying integers. Step 1: Multiply the numbers. 25 x 8 x 2 = 400 Step 2: Determine the sign of the answer. (-) x (-) = (+); (+) x (-) = (-) The sign of the answer is negative. -400

Solution The product is -400.

Rules for Dividing Integers If the signs are alike, the answer is positive. If the signs are different, the answer is negative.

Example 4 Divide: (-20) / (5) = Strategy: Follow the rules for dividing integers. Step 1: Divide the numbers. 20 / 5 = 4 Step 2: Determine the sign of the answer. The signs are different; negative. -4

Solution The quotient is -4.