Integers

1

Integers are whole numbers, which can be positive or negative.

Polarity

The polarity of a number says whether it is positive or negative:-
Numbers bigger than zero are positive, those less than zero are negative.
Zero itself is neutral.

A negative number is written with  a minus sign in front of it.
It is good practice to put negative numbers into brackets e.g. (-6)

 

2

Examples

If you have an account at the bank and you have arranged an overdraft facility then:

2 If you are £6 overdrawn on your account, you owe the bank £6 and therefore have less money available than if you had £12 in your account.

3 If you are £125 overdrawn on your account, you owe the bank more money than if you were £5 overdrawn.

4 If you have £5 in your account, you have more money available than you would if you were £50,000 overdrawn on your account.

 

Addition / Subtraction

5 4

   + means go forwards         -   means go backwards.

 

Example

3 + 4 = 7

Example

3 - 4 = -1

Example

-6 + 2 = -4

1

 

Example
            -1 - 4 =( -5)

2

 

 

Adding a negative number is the same as subtracting its positive counterpart.
(Using the Bank examples above, this could be likened to making a purchase with a debit card)

Examples
            -5 + (-3) =  -5 -3 = -8

 

4

 

 

Subtracting a negative number is the same as adding its positive counterpart.
(Using the Bank examples above, this could be likened to making a purchase with a debit card , then taking the goods back for a refund on the same account.)

Example
            -5 - (-8) = -5 +8 = 3

3

 

Multiplying Integers

 

mu

Like signs produce a positive answer.

Mixed signs produce a negative answer.

 

Examples
                    5 x  8 =  40
            (-5) x  (-8) = 40


            (-5) x  8 = (- 40)
           5 x ( - 8) = (- 40)
      

Dividing Integers

 

div

Like signs produce a positive answer.

Mixed signs produce a negative answer.

Examples
                             40 ÷  8 =  5
                    (- 40) ÷ (- 8) =  5


                   (- 40) ÷ 8 =  (- 5)
                    40 ÷ (- 8) =  (- 5)

 

© Alexander Forrest