Decimal Notation
Decimals represent part of a whole
number. Like whole numbers there
are different place values of
decimals and they can be written
several ways.
Decimal Notation
Decimal Notation
Word Form- Write the whole
number, use the word “and” in place
of the decimal, write the decimal
portion.
 Example: 43.275 “Forty-three and
two hundred seventy-five
thousandths”

Decimal Notation
Number Form- Write using digits in
the correct place value.
 Example: “Five and twelve
hundredths” = 5.12
 Expanded Form- Write an addition
problem using the value of each
digit.
 Example: 5 + 0.1 + 0.02

Rounding Decimals


Underline place value you are rounding to
Look at the digit to the right



If it is 4 or less the underlined digit stays the
same
If it is 5 or more the underline digit goes up
one
The digits to the left stay the same, the
digits to the right get dropped/turn to
zeros
Comparing & Ordering
Fractions
> Greater Than
 < Less Than
 = Equal To
 Compare whole #’s first
 If the whole #’s are the same,
compare decimals starting at the left

Scientific Notation

Scientific Notation
 Where a number is written in two parts:
First: just the digits (with the decimal point placed
after the first digit),
Followed by: ×10 to a power that would put the
decimal point back where it should be.
Scientific Notation

To Change from Number Form to
Scientific Notation:
Move the decimal to the left until the
whole # is between 1 & 9
 Take that # times 10, with an exponent
(the exponent should be the number of
places you moved the decimal)

Scientific Notation

To Change from Scientific Notation
to Number Form:
Look at the exponent
 Move the decimal that many places to
the right.

Add/Subtract Decimals
Line up the decimals
 Add/Subtract like normal

Multiply Decimals
Multiply like normal
 Count the number of digits behind
the decimals in the problem. There
should be the same number of digits
behind the decimal in the product.

Divide Decimals by Whole
Numbers
Move the decimal point straight up
 Divide like normal

Divide Decimals by
Decimals
Move the decimal to the end of the
divisor
 Move the decimal the same # of
places right in the dividend
 Move the decimal straight up.
 Divide like normal
