3. Order of Operations

Problem: There are 2 ways to answer this question:

2 + 3 × 7

We can either

Which is correct?

To reduce confusion and so that we all get the same answer, the following convention is used.

BODMAS

BODMAS is the agreed convention for answering problems that are a mixture of adding, subtracting, multiplying and dividing. It stands for:

B: Do what is inside brackets first
O: Order is important in mathematics!
DM: Do multiplications and divisions as you come to them, from left to right
AS: Finally, do additions and subtractions as you come to them, from left to right.

So for our problem above, the correct answer would be:

2 + 3 × 7

= 2 + 21

= 23


Example 1:

Evaluate 10 − 2 × 3

Answer


Example 2:

Evaluate (10 − 2) × 3

Answer


Example 3:

Simplify -3 + 5 × (72 + 5)

Answer


Example 4:

Simplify 12(5 + 6 × 3) ÷ (4 + 2)

Answer


Example 5:

Simplify -2(x + 5 × 7 + 3)

[Note the difference between the letter "x" and the multiplication operator "×".]

Answer




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