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Sunday, March 6, 2011
Saturday, February 5, 2011
Form 2 - Directed Numbers
Directed NumbersNumbers 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 SubtractionTwo 'pluses' make a plus, two 'minuses' make a plus. A plus and a minus make a minus.
Example3 + (-2)
A plus and a minus make a minus, so this is the same as 3 - 2 = 1
Example(-2) + (-5) = -7
This is the same as (-2) - 5 = -7
Multiplication and DivisionIf two...
