Positive & Negative Numbers
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 a minus.
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
This video explains more about how this works
Multiplication and Division
- If two positive numbers are multiplied together or divided, the answer is positive.
- 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) = (-6)
- (-2) × (-2) = 4
This video explains how to multiply negative numbers
This video shows you how to divide negative numbers