Writing a
number sentence helps organize the information within a math
problem. It's a way of showing the relationship between the
known facts and the
unknowns in the
problem.

Example:

Phil
likes to use his computer to find information on the Internet.
Each hour on-line costs him $1.50. If he searches for 5 hours,
what is the cost?

What are you
asked to find?

the total cost for 5 hours of
on-line time

What information will you use?

$1.50 for each hour and 5 hours of
use

Is
there any information you won't use?

no

What strategy
can you use to find the answer?

You can write a
number sentence to find the total cost of the on-line time. A
number sentence can show how the facts in the problem are
related.

You can write a
number sentence that uses
n to stand for the product.

number
of hours

cost
per hour

total
cost of on-line time

5

x

$1.50

=

n

$1.50 x 5 $7.50

n
=
$7.50

So, Phil needs
$7.50 to pay for
the cost of his time on the Internet.

LOOK BACK

What other strategies could you
have used to solve the problem?

Possible answer: Make a table

Problem:

Nicole spent
$215.75 on computer programs. Lisa spent $75.25 on computer
programs. How much more did Nicole spend than Lisa?

Fact

Question

Read

$215.75 (amount
Nicole spent)
- (minus sign) $75.25 (amount
Lisa spent )
=(equal sign) n (how
much more Nicole spent).