Decimal

“A decimal point

separates the whole number from the places that are less than one.

·

Place

values extend infinitely in two directions from a decimal point.

·

A

number containing a decimal point is called a decimal number or simply

a decimal.”

·

If,

the whole illustration below equals one. How much do the shaded sections equal?

1.

2.

3.

Hundreds

Tens

Ones

Decimal Point

Tenths

Hundredths

Thousandths

8

4

1

.

5

6

2

Reading a number into

the decimals

1.

Say

the first part (left of the decimal) of the number like normal. (if there is one)

2.

Say

“and” where the decimal is.

3.

Say

the second part of the number like normal but end with the last/smallest place

value

Example: eight hundred forty

one AND five hundred sixty two thousandths

Practice:

1.

485.856

–

2.

1835.21

–

3.

881.584

–

4.

684.9 –

5.

38.358 –

Writing

Decimals can be written in standard, written, or expanded forms.

Standard

– # form

·

0.2

·

0.85

·

2.376

·

315.007

Written

= word form

·

Two

tenths

·

Eighty-five

hundredths

·

Two

and three hundred seventy-six

thousandths

·

Three

hundred fifteen and seven

thousandths

Expanded

= equation form broken up by place values.

·

(0

x 1) + (2 X .1)

·

(0

x 1) + (8 x .1) + (5 x .01)

·

(2

x 1) + (3 x .1) + (7 x .01) + (6 x .001)

·

(3

x 100) + (1x 10) + (5 x 1) + (0 x .1) + (0 x .01) + (7 x .001)

Rounding

Decimals Math SOL 4.4 b

Rounding

decimals is the same as rounding any other whole number.

1.

Look

to where you are being asked to round.

2.

Then

look to the number on the right.

a.

5

or higher round up

b.

4

or less leave it alone & drop all the digits to the right of the rounded

place value

3.

Say

your number stopping at the rounded place value.

Example/Practice:

1.

Round

0.876 to the nearest hundredths = .88

2. Round

1.23 to the nearest tenths =

3. Round

32.056 to the nearest hundredths =

4. Round

157.098 to the nearest tenths =

5. Round

5.752 to the nearest hundredths =

Comparing

Decimals Notes Math SOL 4.4 c

> – greater than

< - less than = - equal to Comparing decimals is similar to comparing whole numbers. Look at the highest place value available and figure out which number is larger. Examples: · 0.86 ___ .65 greater than or >

·

1.038 ___ .0038

·

3.248 ___ 3.258

·

7.2 ___ 7.9

·

5.24 ___ 5.34

·

6.07 ___ 6.7