Which operation should be performed first according to the order of operations of #21-5+24-:3+90xx4#?
2 Answers
Explanation:
Whether you are taught PEMDAS, BODMAS or BIDMAS, the order of operations is the same:
P - Parentheses
E - Exponents
MD - Multiplication and Division (left to right)
AS - Addition and Subtraction (left to right)
Note that the MD in PEMDAS does not mean that you should do multiplication before division. They are of equal priority, so when you get to MD perform them left to right. Similarly for AD, Addition and Subtraction.
So in our example, the first operation you would perform is
The actual result of performing operations in order on this example is as follows:
#21 - 5 + color(red)(24 -: 3) + 90 xx 4#
#=21 - 5 + 8 + color(red)(90 xx 4)#
#=color(red)(21 - 5) + 8 + 360#
#=color(red)(16 + 8) + 360#
#=color(red)(24 + 360)#
#=384#
There is not actually ONE single operation which should be done first in this expression. There are three possible operations which can be done in the first line of working.
Explanation:
There is not actually ONE operation which should be done first in this expression.
There are 4 terms - you can work in any of the terms independently from the others. We have:
While the obvious calculations are in the third and the fourth terms, we could also combine the first and second terms already, as there is nothing more that can be done with them.
So the next step could read as:
However, it is probably better to leave all the additions and subtractions to the LAST step.
It is much less confusing and far easier to do the additions first and then the subtraction.
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