A positive number is any number that is greater than zero and has a positive sign ( + ).

Often the positive sign is understood and not written in front of the number. For

example, the number +8 is usually written as 8. A negative number is any number

that is less than zero and is written with a negative sign (-). For example, a negative

e ight is written as -8.

Multiplication a nd Division of Positive and Negative Numbers

When two positive numbers or two negative numbers are multiplied, the answer is

positive(+).

2 X 3 = 6 The + sign ( +6) is understood.

(-2) X (-3) = 6

When a positive number and a negative number are multiplied, the answer is negative (-).

2 X (-3) = -6

(-2) X 3 = -6

The rules for the division of positive and negative numbers are the same as the rules

for multiplication. When two positive numbers or two negative numbers are divided, the

answer is positive ( + ).

6

- = 2

3

-6 - = 2

-3

When a positive number and a negative number are divided, the answer is negative (-).

-6 6 - = -2 – = -2

3 -3

Addition of Positive and Negative Numbers

When positive numbers are added, the sign of the answer is positive.

3 + 4 = 7 The + sign (+7) is understood.

When negative numbers are added, the sign of the answer is negative.

-3 + (-4) = -7

When a positive number and a negative number are added, the smaller number is subtracted

from the larger number, and the result has the same sign as the larger number.

12 + (-15) = -3

Subtraction of Positive and Negative Numbers

When two numbers are subtracted, change the sign of the number to be subtracted and

follow the rules for addition shown above.

12-(+5) = 12- 5 = 7

12- (-5) = -12 + 5 = -7

Calculator Operations

On your calculator, there are four keys that are used for basic mathematical operations. The

change sign I+/-) key is used to change the sign of a number.

To practice these basic calculations on the calculator, work through the problem

going from the left to the right, doing the operations in the order they occur. If your calculator

has a change sign l+t-1 key, a negative number is entered by pressing the number

and then pressing the change sign