Given the expression
5 + 4 × 2 + 6 - 2 × 2 - 1
We would want to insert the parentheses for the sum that is not division or multiplication so we can work out the sum inside the parentheses first. We have the option to insert the parentheses either for '5 + 4' or for '2 + 6' or for '6 - 2' or for '2 - 1'
Using trial and error:
(5 + 4) × 2 + 6 - 2 × 2 - 1 ⇒ Working this out following BIDMAS
9 × 2 + 6 - 2 × 2 - 1
18 + 6 - 4 - 1
24 - 4 - 1
19
The parentheses inserted for the sum 5 + 4 gives the answer 19
