Operations in the right order
When faced with a mathematical expression comprising several operations or parentheses, the result may be affected by the order in which the various operations are tackled e.g.
4⋅7−2
the result is influenced if we take the multiplication first:
28−2=26
Or if we begin with the subtraction:
4⋅5=20
To avoid misunderstandings mathematicians have established an order of operations so that we always arrive at the same result.
- Simplify the expressions inside parentheses ( ), brackets [ ], braces { } and fractions bars.
- Evaluate all powers.
- Do all multiplications and division from left to right.
- Do all addition and subtractions from left to right.
An example of this appears if we were to ask ourselves how many hours a person works over two days, if they work 4 hours before lunch and 3 hours after lunch. We first work out how many hours the person work each day:
4+3=7
and then multiply that with the number of working days:
7⋅2=14
if we instead were to write this as an expression, we would need to use parentheses in order to calculate the addition first:
(4+3)⋅2=14
Video lesson
Evaluate the expression
2⋅[4+(4−2)2−3]+(142)