McGraw-Hill/Irwin ©2008 The McGraw-Hill Companies, All Rights Reserved Chapter 3 Decimals

McGraw-Hill/Irwin ©2008 The McGraw-Hill Companies, All Rights Reserved Explain the place values of whole numbers and decimals; round decimals Convert decimal fractions to decimals, proper fractions to decimals, mixed numbers to decimals, and pure and mixed decimals to decimal fractions Decimals #3 Learning Unit Objectives Rounding Decimals; Fraction and Decimal Conversions LU3.1

McGraw-Hill/Irwin ©2008 The McGraw-Hill Companies, All Rights Reserved Add, subtract, multiply, and divide decimals Multiply and divide decimals by shortcut methods Complete decimal applications in foreign currency Decimals #3 Learning Unit Objectives Adding, Subtracting, Multiplying, and Dividing Decimals LU3.2

3-4 Table Bag of M&M’s Decimal Percent ColorFraction (hundredth)(hundredth) Yellow Yellow % 55 Red Red % 55 Blue Blue % 55 Orange Orange % 55 Brown Brown % 55 Green Green % 55 Total Total % 55 = 1

3-5 Decimal place-value chart Figure 3.1 HundredsThousandsTensOnes Hundredths Tenths Ten Thousandths Thousandths Hundred Thousandths 1, , , ,000 Decimal Point and Whole Number Groups Decimal Place Values

3-6 Rounding Decimals Step 1. Identify the place value of the digit you want to round Step 2. Identify the digit to the right. If 5 or more, increase the identified digit by 1. If less than 5 do not change Step 3. Drop all digits to the right of the identified digit.33

3-7 Rounding Decimals $ >The 6 is in the hundredths place value > The 5 is in the tenths place value > The 4 is in the ten thousandths place value

3-8 Converting Decimal Fractions to Decimals 2 Steps 1. Count the number of zeros in the denominator. 2. Place the numerator of the decimal fraction to the right of the decimal point the same number of places as you have zeros in the denominator. Do not go over the total number of denominator zeros. Fraction Decimal # of places , ,000

3-9 Converting Proper Fractions to Decimals EQUALS.75 Step 1

3-10 Converting Mixed Numbers to Decimals (Step 2) (Step 1)

3-11 Converting Pure Decimals to Decimal Fractions Step 1 Step 2 Step 3 Places

3-12 Converting Mixed Decimals to Decimal Fractions Step 1 Step 2 Step 3 Places =17

3-13 Adding Decimals Add:

3-14 Subtracting Decimals Subtract:

3-15 Multiplying Decimals 2.36 x decimal places decimal places 8.52 (2 decimal places) x 6.7 (1 decimal places) Need to add zero

3-16 Dividing Decimals Step 1. Make the divisor a whole number by moving the decimal point to the right Step 2. Move the decimal point in the dividend to the right the same number of places as in step 1. If there are not enough places, add zeros to the right of the dividend. Step 3. Place the decimal point in the quotient above the new decimal point in the dividend. Divide as usual Example

3-17 Key Currency Cross Rates Decimals Applications in Foreign Currency $299 x = pounds Check pounds x = $ DollarEuroPoundSFrancPesoYenCdnDlr Canada ….. Japan … Mexico … Switzerland … U.K … Euro.79300… U.S.…

3-18 Shortcuts for Multiples of x x x Count the zeros in the multiplier Move the decimal point the same number of spaces to the right Multiplication

3-19 Shortcuts for Multiples of / / / Count the zeros in the divisor Move the decimal point the same number of spaces to the left Division

3-20 Problem 3-62: $30,000 x = 56,355 pounds Solution: Check: 56, 355 x = $29,998 (due to rounding)

3-21 Problem 3-69: 2 x $29.95 = $59.90 $0.145 x = + $59.57 $ Solution:

3-22 Problem 3-74: $ $ $3.75 = $ sq. yards sq. yards sq. yards = x $6, Solution:

3-23 Problem 3-76: Laundry Detergent A $2.00 for 37 ounces $2.00 ÷ 37 = $.05 Laundry Detergent B $2.37 for 38 ounces $2.37 ÷ 38 = $.06 Mustard A $.88 for 6 ounces $.88 ÷ 6 = $.15 Mustard B $1.61 for 12.5 ounces $1.61 ÷ 12.5 = $.13 Canned Tuna A $1.09 for 6 ounces $1.09 ÷ 6 = $.18 Canned Tuna B $1.29 for 8.75 ounces $1.29 ÷ 8.75 = $.15 Solution: