We follow the order of BODMAS to perform matjematical operations.B:bracket;O:of;D:division;M:multiplication;A:addition;S:subtraction.
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First the calculations must be done form left to right
next  do the calculations in brackets (parenthesis) are done first.
 When you have more than one set of brackets, do the inner brackets first
and then remaining brackets
if there are exponents then do the exponents calculations
then multiply and divide in the order of operations they ocuur
and then add and subtract in the order of operations they occur

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