Rules for Multiplication

$\Large (+)(+) = (+) $

$\Large (+)(-) = (-) $

$\Large (-)(+) = (-) $

$\Large (-)(-) = (+) $

Rules for Division

$$ {\Large (+)\over \Large (+)} \Large = (+) $$

$$ {\Large (+) \over \Large (-)}\Large = (-) $$

$$ {\Large (-) \over \Large (+)} \Large = (-) $$

$$ {\Large (-)\over \Large (-)} \Large = (+) $$

Examples

Operator Precedence ....This is the order in which calculations are performed.

BIDMAS - brackets, indices, division, multiplication, add, subtract

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example #1

4 + 7 x 2 - 3(5 + 9)............work out what is inside the brackets

4 + 7 x 2 - 3(14)................do the multiplication 7 x 2 and 3 x 14

4 + 14 - 42 .......................add the 4 and 14

18 - 42..............................subtract the 42

-24

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example #2

7(12-9 ) x (3+4) - 7 + 8 x 20/5.............work out what is inside the brackets

7(12-9 ) x (3+4) - 7 + 8 x 20/5.............division next

7(3) x (7) - 7 + 8 x 20/5.......................multiplication

7 x 3 x (7) - 7 + 8 x 4..........................more multiplication

21 x 7 - 7 + 32....................................addition

147 - 7 +32.........................................subtraction

179 -7

172

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example #3

3 + 9(6 - 2) - 12/3 + 4 x 7....work out what is inside the brackets

3 + 9(4) - 12/3 + 4 x 7.........division next

3 + 9 x 4 - 4 + 4 x 7.............multiplication

3 + 36 - 4 + 4 x 7.................more multiplication

3 + 36 - 4 + 28 ...................addition

67 - 4..................................subtraction

63

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