Math 7 lesson 10 representing problems with negative numbers

•At the end of this lesson, you will be able to
write mathematical representations of word
problems involving negative numbers.

•In mathematics, numbers can be classified into
three categories according to sign: positive,
negative and zero. All real numbers fall into one of
these categories.

The concept of negative numbers has to do with the
loss or taking away of an object that you do not have.
Oftentimes, borrowing money can be represented as a
negative number.

Which of the following is a negative number?
a. 9
b. 0
c. -7
d. 2
The answer is c. -7. This is the only answer that has a
negative sign.

In the real world, is often used to represent the
concept of nothingness. It might seem strange at first,
but we can actually have less than nothing. These
quantities are represented by the negative numbers. For
example, you can start with nothing and take or borrow
something from a friend. Because you now owe your
friend, you have less than nothing, which can be
expressed as a negative number.

You borrowed ₱6 from your friend for lunch. Which of
the numbers below represents this situation?
a. -6
b. 6
c. -3
d. 3
The answer is a. -6. We use the negative sign because
we are using money we do not have. Borrowing ₱6 is
represented as -6.

•The temperature in the refrigerator is 5℃. After a
few minutes, you check again and the temperature
drops by 2°. What is a good representation for the
temperature drop?
In this case, a 2° drop in temperature is represented
as -2.

•Sam counted 15 chairs in the classroom. If a
classmate borrows 3 chairs to use outside, what is
the representation for the borrowed chairs?

•Sam counted 15 chairs in the classroom. If a
classmate borrows 3 chairs to use outside, what is
the representation for the borrowed chairs?
•Three borrowed chairs can be represented as -3.

•Clara has 6 pieces of candy. She gives 1 piece to
Mara and 3 pieces to Lara. What is the representation
of the candies she gave away?

•Clara has 6 pieces of candy. She gives 1 piece to
Mara and 3 pieces to Lara. What is the representation
of the candies she gave away?
•Answer: (-1) + (-3) = -4

•The number 0 is the only number without a
sign. It is neither negative nor positive.
•Any action that pertains to a decrease can
be represented as a negative number.

1. Which of the following situations is most
directly related to the concept of a negative
number?
a. having fun
b. losing something
c. having nothing at all
d. gaining something

2. Which side of the number line contains the
negative numbers?
a. both sides
b. the right side
c. the left side
d. the middle

3. Which of the following is a negative number?
a. 0
b. 1
c. -2
d. 4

4. You have 9 carrots. You eat 5 of them. Which
of the following represents the number of
carrots you ate?
a. 4
b. -5
c. 5
d. -4

5. A pizza has 8 slices. You eat half of the
slices. Your brother eats 2 more slices. How
many slices of pizza are left?
a. 2
b. -2
c. 6
d. -4

6. What number corresponds to the encircled
mark on the number line?
a. 4
b. -3
c. 3
d. -4

7. The temperature dropped 13.5° below zero.
Which number represents this situation?
a. 3.5
b. -3.5
c. 13.5
d. -13.5

8. You are standing at 2 on the number line. You
move 7 units to the left. Where do you stop?
a. 9
b. -5
c. -7
d. -2

9. You have ₱50. You buy lunch for ₱35. Later,
you buy an after-school snack for ₱25. However,
since you do not have enough money, you have to
borrow some from your friend. How much money
do you need to borrow?
a. ₱25
b. - ₱35
c. ₱10
d. ₱60

10. Your sister wants to buy a doll, but she only
has ₱200. You lend her ₱500 to help her
out. She later pays you back ₱300. How
much does she owe you now?
a. ₱200
b. ₱500
c. ₱700
d. ₱300

Math 7 lesson 10 representing problems with negative numbers

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Math 7 lesson 10 representing problems with negative numbers