| + | sum(or total) of | addition | ||
| - | difference between | subtraction | ||
| x | product of | multiplication | ||
| / | quotient of | division |
Rules for Multiplication & Division
a '+' multiplied by a '+' gives a '+'
a '+ ' multiplied by a ' - ' gives a ' - '
a ' - ' multiplied by a '+' also gives a ' - '
a ' - ' multiplied by a ' - ' gives a '+'
a '+' divided by a '+' gives a '+'
a '+ ' divided by a ' - ' gives a ' - '
a ' - 'divided by a '+' also gives a ' - '
a ' - ' divided by a ' - ' gives a '+'
Examples
| (+3)(-4)= -12 | (-2)/(+9)= -(2/9) | |||
| (-5)(-2)= +10 | (+3)/(-5)= -(3/5) | |||
| (+7)(+2)= +14 | (+6)/(+7)= +(6/7) | |||
| (-9)(+5)= -45 | (-5)/(-2)= +(5/2) |
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)
4 + 7 x 2 - 3(14).......work out what is inside the brackets
4 + 14 - 42...............do the multiplication 7 x 2 and 3 x 14
18 - 42 ....................add the 4 and 14
-24 ..........................subtract the 42
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example #2
7(12-9 ) x (3+4) - 7 + 8 x 20/5
7(12-9 ) x (3+4) - 7 + 8 x 20/5.....work out what is inside the brackets
7(3) x (7) - 7 + 8 x 20/5................division next
7 x 3 x (7) - 7 + 8 x 4....................multiplication
21 x 7 - 7 + 32..............................more multiplication
147 - 7 +32...................................addition
179 -7...........................................subtraction
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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