Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 4.3 Adding and Subtracting Decimals

Martin-Gay, Basic Mathematics, 4e 22 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Adding and Subtracting Decimals Adding or Subtracting Decimals Step 1: Write the decimals so that the decimal points line up vertically. Step 2: Add or subtract as with whole numbers. Step 3: Place the decimal point in the sum or difference so that it lines up vertically with the decimal points in the problem.

Martin-Gay, Basic Mathematics, 4e 33 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Adding Decimals StepExample Step 1: Write the decimals so that the decimal points line up vertically. Add: Step 2: Add or subtract as with whole numbers. Step 3: Place the decimal point in the sum or difference so that it lines up vertically with the decimal points in the problem.

Martin-Gay, Basic Mathematics, 4e 44 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. ProblemsAnswers 1a. 1b. 1c. P 264 Practice Problems Adding Decimals

Martin-Gay, Basic Mathematics, 4e 55 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Example Add: Insert one zero

Martin-Gay, Basic Mathematics, 4e 66 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Practice ProblemsAnswers 2a. 2b. 3. P 265 Adding Decimals

Martin-Gay, Basic Mathematics, 4e 77 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Example Subtract: – 5.9 Insert decimal point and one zero

Martin-Gay, Basic Mathematics, 4e 88 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Example Subtract: 28 – 3.3 Insert decimal point and one zero 24.7 Line up decimal points Subtract.

Martin-Gay, Basic Mathematics, 4e 99 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Subtracting Decimals Practice Problem 4a. SOLUTION – 15.9 P 265

Martin-Gay, Basic Mathematics, 4e 10 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Subtracting Decimals Practice Problem 4b. SOLUTION – P 265

Martin-Gay, Basic Mathematics, 4e 11 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Subtracting Decimals Practice Problem 5a. SOLUTION 5.8– 3.92 P 266

Martin-Gay, Basic Mathematics, 4e 12 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Subtracting Decimals - optional Practice Problem 5b. P 266 Practice Problem 6a. Practice Problem 6b.

Martin-Gay, Basic Mathematics, 4e 13 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Estimating when Adding or Subtracting Decimals To help avoid errors, we can estimate to see if our answer is reasonable by rounding the given numbers and adding or subtracting. Example: 7.6 – 2.1 rounds to Exact Since the exact answer is close, it is reasonable.

Martin-Gay, Basic Mathematics, 4e 14 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Example A pair of eyeglasses costs a total of $ The frames of the glasses are $ How much do the lenses of the eyeglasses cost? The lenses of the eyeglasses cost $

Martin-Gay, Basic Mathematics, 4e 15 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Solving Problems by Adding or Subtracting Decimals Practice Problem 8 SOLUTION Find the total monthly cost of owning and operating a certain automobile given the expenses shown? P 267

Martin-Gay, Basic Mathematics, 4e 16 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. DONE

Martin-Gay, Basic Mathematics, 4e 17 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Subtracting Decimals P 266 Practice Problem 7b. Practice Problem 7a.