Transcript Sec. 5.3
OBJECTIVES
A
Multiply using
decimal notation.
B Convert from
notation like 45.7
million to standard
notation, and
convert between
dollars and cents.
To multiply using decimals:
a) Ignore the decimal points,
and multiply as though both
factors are whole numbers.
0.8 0.43
2
0.43
0.8
344
b) Locate the decimal point in
the result. The number of decimal
places in the product is the sum of the 0.43
0.8
number of places in the factors.
(count places from the right).
0.344
Section 5.3
Ignore the
decimal points
for now.
(2 decimal places)
(1 decimal place)
(3 decimal places)
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To multiply any number by 0.1, 0.01, 0.001, and so on,
a) count the number of decimal
0.001 34.45678
places in the tenth, hundredth,
or thousandth, and so on, and
3 places
b) move the decimal
point that many places
to the left.
0.001 (6.4)
0.001 34.45678 = 0.03445678
Move 3 places
to the left.
0.001 34.45678 = 0.03445678
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To multiply any number by 10, 100, 1000, and so on,
a) count the number of
zeros and
100 4.1
1000 34.45678
3 zeros
b) move the decimal
point that many places
to the right.
1000 34.45678 = 34.456.78
Move 3 places
to the right.
1000 34.45678 = 34,456.78
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0.001 (6.4)
0.0001 721.4
1000 (2.3046)
100 4.1
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Naming Large Numbers
1 hundred = 100 = 10 10 = 102
EXAMPLE:
2 zeros
1 thousand = 1000 = 10 10 10 = 103
3 zeros
1 million = 1,000,000 = 10 10 10 10 10 10 = 106
6 zeros
1 billion = 1, 000,000,000 = 109
9 zeros
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
1 trillion = 1,000,000,000,000 = 1012
12 zeros
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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.
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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.
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