Numbers can either be positive or negative. Often brackets are put around
negative numbers to make them easier to read, e.g. (-2). If a number is
positive, the + is usually missed out before the number. So 3 is really (+3).
Adding and multiplying combinations of positive and negative numbers can cause
confusion and so care must be taken.
Addition and Subtraction
Two 'pluses' make a plus, two 'minuses' make a plus. A plus and a minus make
3 + (-2)
A plus and a minus make a minus, so this is the
same as 3 - 2 = 1
(-2) + (-5) = -7
This is the same as (-2) - 5 = -7
Multiplication and Division
If two positive numbers are multiplied together or divided, the answer is
If two negative numbers are multiplied together or divided, the
answer is positive.
If a positive and a negative number are multiplied or
divided, the answer is negative.
(-2) ÷ (-4) = ½
(8) ÷ (-2) = (-4)
2 × (-3) =
(-2) × (-2) = 4
Copyright © Matthew Pinkney 2003