Exercise 1 Page p12

We want to calculate the sum of the given quantities.

- 8 + 13

To do so, remember that addition can be thought of as moving to the right on a number line. Therefore, adding

13

to

- 8

is like moving

13

steps to the right of

- 8 .

We can check our answer by finding the sum of the given quantities in a calculator. Let's check our math!

We obtain the same result as before. Therefore, we were correct!

Operations with Integers

As we can see, we can apply operations between integers with same or different sign. Let's see what happens in each case.

Sign	Operation	Result	Example
$+ +$	Addition	Positive sum	$4 + 4 = 8$
$- -$	Addition	Negative sum	$- 4 + (- 8) = - 12$
$+ +$	Product	Negative Product	$4 (4) = 16$
$- -$	Product	Positive product	$(- 4) (- 4) = 16$
$+ +$	Quotient	Positive quotient	$\frac{1 6}{4} = 4$
$- -$	Quotient	Positive quotient	$\frac{- 1 6}{- 4} = 4$

We need to be aware when the signs are different. In that case, we will have the following results.

If the negative number is greater than the positive number, then their sum will be negative.
If the positive number is greater than the negative, then their sum will be positive.
The product of quotient of two numbers having different signs will be negative.

For those of you who are interested in learning more about operations with integers, you can read more about them on the following pages.