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Maths I
Order of operation
Do you remember BODMAS? It stands for 'brackets', 'other', 'division', 'multiplication', 'addition' and 'subtraction'. The order in which we carry out a calculation is important.
What is 2 + 3 x 4 ?
If we calculate the ‘2 + 3’ part first, we get:
(2 + 3) x 4 = 5 x 4
= 20
If we calculate the ‘3 x 4’ part first, we get:
2 + (3 x 4) = 2 + 12
= 14
These are obviously two different answers - but which one is correct?
BODMAS tells us that 'multiplication' comes before 'addition', so the second answer is correct:
2 + 3 x 4 = 2 + 12 = 14
Worked example:
Calculate: 3 x (7 - 3)
Solution
In this question, we have a bracket, a subtraction and a multiplication.
BODMAS tells us that brackets come first, so we calculate:
3 x (7 - 3) = 3 x 4 = 12
Calculate: 2 + 3 x 5 - 4
Did you get 13 ? Well done.
If not, remember that multiplication comes before addition and subtraction, so we have: 2 + 3 x 5 - 4 = 2 + 15 - 4 = 13
Now try a Test Bite
Links
Scottish Qualifications Authority Maths resources, including Past Papers, Arrangements Documents, and Marking Guidelines.
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