Basic Mathematics for College Students

48 Chapter 1 Whole Numbers

The Language of Mathematics Here are some key words and phrases that

are often used to indicate multiplication:

double triple twice of times

EXAMPLE (^10) Weight Lifting In 1983, Stefan Topurov of Bulgaria was
the first man to lift three times his body weight over his head. If he weighed 132
pounds at the time, how much weight did he lift over his head?
Strategy To find how much weight he lifted over his head, we will multiply his
body weight by 3.
WHY We can use multiplication to determine the result when a quantity increases
in size by 2 times, 3 times, 4 times, and so on.
Solution
We translate the words of the problem to numbers and symbols.
was times

= 3 132

Use vertical form to perform the multiplication:

Stefan Topurov lifted 396 pounds over his head.

132

 3

396



The amount he

lifted over his head

3 his body weight.

The amount he

lifted over his head

Self Check 10

INSECTSLeaf cutter ants can

carry pieces of leaves that weigh

30 times their body weight. How

much can an ant lift if it weighs

25 milligrams?

Now TryProblem 99

Using Your CALCULATOR The Multiplication Key: Seconds in a Year

There are 60 seconds in 1 minute, 60 minutes in 1 hour, 24 hours in 1 day, and

365 days in 1 year. We can find the number of seconds in 1 year using the

multiplication key on a calculator.

60 60 24 365

One some calculator models, the key is pressed instead of the

for the result to be displayed.

There are 31,536,000 seconds in 1 year.

ENTER 

    31536000



7 Find the area of a rectangle.

One important application of multiplication is finding the area of a rectangle. The area

of a rectangleis the measure of the amount of surface it encloses. Area is measured in

square units, such as square inches (written in.^2 ) or square centimeters (written cm^2 ),

as shown below.

1 in. 1 in.

1 in.

One square inch (1 in.^2 )

1 in.

1 cm 1 cm

1 cm

One square centimeter (1 cm^2 )

1 cm