To multiply using decimals: 0.8 0.43 a) Ignore the decimal points, and multiply as though both factors are whole numbers. b) Locate the decimal point in the result. The number of decimal places in the product is the sum of the number of places in the factors. (count places from the right). 2 (2 decimal places) (1 decimal place) (3 decimal places) Ignore the decimal points for now. Section 5.31 A OBJECTIVES Multiply using decimal notation. BConvert from notation like 45.7 million to standard notation, and convert between dollars and cents.
Section 5.32
3 To multiply any number by 0.1, 0.01, 0.001, and so on, a) count the number of decimal places in the tenth, hundredth, or thousandth, and so on, and b) move the decimal point that many places to the left places = Move 3 places to the left = (6.4)
Section 5.34 To multiply any number by 10, 100, 1000, and so on, a) count the number of zeros and b) move the decimal point that many places to the right zeros 1000 = Move 3 places to the right = 34, 4.1
Section (6.4) (2.3046)
Section 5.36 Naming Large Numbers 1 hundred = 100 = 10 10 = thousand = 1000 = 10 10 10 = million = 1,000,000 = 10 10 10 10 10 10 = billion = 1, 000,000,000 = trillion = 1,000,000,000,000 = zeros 3 zeros 6 zeros 9 zeros 12 zeros EXAMPLE: Convert the number in this sentence to standard notation: The estimated world population as of July 2005 was 6.4 billion people. 6.4 billion = 6.4 1 billion
Section 5.37 Dollars to Cents Conversions To convert from dollars to cents, move the decimal point two places to the right and change the $ sign in front to a ¢ sign at the end. Cents to Dollars Conversions To convert from cents to dollars, move the decimal point two places to the left and change the ¢ sign at the end to a $ in front.
Section 5.38 Homework: Problems 33, 41, 45 - copy the problem, multiply showing all work. Problem 55 – copy the problem and give the answer (146₵ = $1.46) Problem 59 – copy the number in words, then give the number is standard notation.