Decimals

APPLICATIONS
19. Tel-Sales, Inc., a prepaid phone card company in Oklahoma
City, sells phone cards for $19.89. Write the card cost in
words.
21. GameStop ® reported a quarterly gross margin of 839.18
dollars in millions of dollars. Write the reported gross
margin in millions of dollars in words.
3-2 OPERATIONS WITH DECIMALS
LEARNING OUTCOMES
1 Add and subtract decimals.
2 Multiply decimals.
3 Divide decimals.
1 Add and subtract decimals.
20. Destiny Telecom of Oakland, California, introduced a Braille
prepaid phone card that costs fourteen dollars and seventy
cents. Write the digits to show Destiny’s sales figure.
22. Gannett Company reported a quarterly income before tax of
negative five thousand, three hundred eighty seven and
twenty-four hundredths dollars in millions of dollars. Write
the reported gross margin in millions of dollars in words.
Some math skills are used more often than others. Adding and subtracting decimal numbers are
regularly used in transactions involving money. To increase your awareness of the use of decimals,
refer to your paycheck stub, grocery store receipt, fast-food ticket, odometer on your car,
bills you receive each month, and checking account statement balance.
HOW TO
Add or subtract decimals
1. Write the numbers in a vertical column, aligning digits
according to their place values.
2. Attach extra zeros to the right end of each decimal
number so that each number has the same quantity of
digits to the right of the decimal point. It is also acceptable
to assume blank places to be zero.
3. Add or subtract as though the numbers are whole numbers.
4. Place the decimal point in the sum or difference to align with
the decimal point in the addends or subtrahend and minuend.
TIP
Add 32 + 2.55 + 8.85 + 0.625.
32
2.55
8.85
0.625
44.025
Unwritten Decimals
When we write whole numbers using numerals, we usually omit the decimal point; the decimal
point is understood to be at the end of the whole number. Therefore, any whole number, such as
32, can be written without a decimal (32) or with a decimal (32.).
TIP
Aligning Decimals in Addition or Subtraction
A common mistake in adding decimals is to misalign the digits or decimal points.
32
2.55
8.85
0.625
44.025
CORRECT
All digits and decimal
points are aligned
correctly.
32
2.55
8.85
0.625
1.797
INCORRECT
;
;
not aligned correctly
not aligned correctly
DECIMALS
85