Section 5.1 1

Given decimal notation, write a word name. Convert between decimal notation and fraction notation. Given a pair of numbers in decimal notation, tell which is larger. Round decimal notation to the nearest thousandth, hundredth,

tenth, one, ten, hundred, or thousand.

Section 5.1 2

Place-Value Chart

Hu

ndre

ds

Te

ns

On

es

Te

nths

Hu

ndre

dths

Th

ousa

ndths

Te

n-T

hou

san

dths

Hu

ndre

d-T

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san

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100 10 1 1/10 1/100 1/1000 1/10,000 1/100,000

4 2 . 3 2 4 5

The decimal notation 42.3245 means

4 tens + 2 ones + 3 tenths + 2 hundredths + 4 thousandths + 5 ten-thousandths

We read this number as

“Forty-two and three thousand two hundred forty-five ten-thousandths.”

The decimal point is read as “and”.

Section 5.1 3

To Write a Word Name from Decimal Notation

a) write a word name for the whole number (the number named to the left of the decimal point),

b) write the word “and” for the decimal point, and

c) write a word name for the number named to theright of the decimal point, followed by the place value of the last digit.

Three hundred ninety-seven

Three hundred ninety-seven and

Three hundred ninety-seven and six hundred eighty-five thousandths

397.685

397.685

397.685

Section 5.1 4

•Write a word name for the number in this sentence: The top women’s time for the 50 yard freestyle is 22.62 seconds.

• Write a word name for the number in this sentence: The one-mile (1.609-km) land speed record is 1,227.985 km/h, set by Andy Green in Thrust SSC in the Black Rock Desert, Nevada, USA, on October 15, 1997.

Section 5.1 5

Finding fraction notation (improper and mixed number):

If you read the number properly, the decimal notation and the mixed number are the same.

4273.427 3

10003427

1000

• Write fraction notation for 0.924. Do not simplify.

• Write 17.77 as a fraction and as a mixed numeral

Section 5.1 6

Going from Fraction Notation to Decimal Notation When the Denominators are a Power of Ten

Write decimal notation for each.

53

10

11

1000

134,027

10,000

Section 5.1 7

Comparing Numbers in Decimal Notation – • Change one or more of the numbers so they

all go out to the same number of decimal places.

• Do this by adding zeros.Which is larger 3.201 or 3.2? Which is larger 0.08 or 0.105?

Section 5.1 8

To round to a certain place:

a) Locate the digit in that place.

b) Consider the digit to the right.

c) If the digit to the right is 5 or greater, round up; if the digit to the right is 4 or lower, round down.

Section 5.1 9

Round 0.072 to the nearest tenth.

Round 34.7824 to the nearest hundredth.

Homework:Problems 1,9 - copy the number, then write the number is wordsProblem 51 – copy the problem, answer the question, justify your answer in words or by showing work.Problems 83, 85 – copy the original number, state to what place you are rounding, give the answer, justify your answer in words.