Brackets first
Do the inside before the outside.
Irfan’s change
Irfan paid ₹100 for biscuits (₹15) and toor dal (₹56). The expression 100 − 15 + 56 gave 141, more than he paid! That is absurd.
Which brackets make the expression say what really happened?
What this lesson covers
The idea
When evaluating an expression having brackets, the values of the expressions inside the brackets are found first, before performing the other operations.
Irfan’s change
Irfan paid ₹100 for biscuits (₹15) and toor dal (₹56). The expression 100 − 15 + 56 gave 141, more than he paid! That is absurd.
Which brackets make the expression say what really happened?
- 100 − (15 + 56)
- (100 − 15) + 56
- I am not sure yet
Brackets say what is first
Tap the operation to do next. If there are brackets, they come first.
Inside first
Brackets can put the multiplication first or the addition first. You choose, and everyone gets the same answer.
When evaluating an expression with brackets, first find the values of the expressions inside the brackets, then do the other operations.
- Expression | Inside first | Value
- 30 + (5 × 4) | 5 × 4 = 20 | 50
- (30 + 5) × 4 | 30 + 5 = 35 | 140
- 100 − (15 + 56) | 15 + 56 = 71 | 29
Notes
When evaluating an expression with brackets, find the values inside the brackets first, then do the other operations.
Check yourself
Work out 50 − (12 + 8).
Answer: 30
12 + 8 = 20 (inside the brackets), then 50 − 20 = 30.
Which expression has the value 20?
Work out 24 ÷ (4 + 2).
Answer: 4
4 + 2 = 6, then 24 ÷ 6 = 4.
- (4 + 6) × 2 — correct. Yes! 4 + 6 = 10 in the brackets, then 10 × 2 = 20.
- 4 + (6 × 2). 6 × 2 = 12 in the brackets, then 4 + 12 = 16.
- (4 + 6) + 2. 4 + 6 = 10, then 10 + 2 = 12.