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).
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?
