What comes first?
In the expression 12 - 4 + 2, which operation do you do first?
Subtraction (work left to right for addition and subtraction).
Solve: 10 + 2 x 5
20 (2 x 5 = 10, then 10 + 10 = 20)
Solve: (4 + 2) x 3
18 (4 + 2 = 6, then 6 x 3 = 18).
True or False: To solve 8 - 2 x 3, you can subtract 8 - 2 first to get 6, then multiply by 3 to get 18.
False. You must multiply 2 x 3 first. The correct answer is 2.
Solve: 2 x (15 ÷ 3 + 8 - 4) + 6
24 (Inside: 5 + 8 - 4 = 9. Outside: 2 x 9 + 6 = 24)
In the expression 5 + 3 x 4, which operation do you do first?
Multiplication (3 x 4)
Solve: 15 - 3 x 2
9 (3 x 2 = 6, then 15 - 6 = 9).
Solve: 20 - (5 + 5)
10 (5 + 5 = 10, then 20 - 10 = 10)
Spot the error: Amy solved 10 + 5 x 2 by doing
10 + 5 = 15, then 15 x 2 = 30. What did she do wrong?
She added before multiplying. She should have multiplied 5 x 2 = 10 first, making the real answer 20.
Solve: 40 ÷ (24 - 4 x 5 + 6) - 1
3 (Inside: 24 - 20 + 6 = 10. Outside: 40 ÷ 10 - 1 = 3)
In the expression (8 - 2) + 6 x 5, which part do you calculate first?
Parentheses (8 - 2)
Solve: 24 ÷ 4 + 2
8 (24 ÷ 4 = 6, then 6 + 2 = 8)
Solve: 6 x (10 - 7) + 2
20 (10 - 7 = 3, then 6 x 3 = 18, then 18 + 2 = 20)
Spot the error: Leo solved (9 - 3) x 2 and got 3 because he did 9 - 3 = 6, then 6 ÷ 2. What is his mistake?
He changed the multiplication sign to division. It should be 6 x 2 = 12.
Solve: 5 x (36 ÷ 6 + 12 - 8) + 4 - 7
47 (Inside: 6 + 12 - 8 = 10.
Outside: 5 x 10 + 4 - 7 = 47).
In the expression 20 ÷ 4 x 2, do you multiply or divide first?
Divide (20 ÷ 4, because you work left to right for multiplication and division)
Solve: 20 - 4 x 2 + 5
17 (4 x 2 = 8, then 20 - 8 = 12, then 12 + 5 = 17)
Solve: (12 ÷ 3) + (8 x 2)
20 (12 ÷ 3 = 4 and 8 x 2 = 16, then 4 + 16 = 20)
Spot the error: For 16 - 4 x 2 + 1, Ben got 25. He went strictly left-to-right
(16 - 4 = 12, 12 x 2 = 24, 24 + 1 = 25). Where did he mess up?
He ignored the order of operations and didn't do multiplication (4 x 2) first. The real answer is 9.
Solve: 3 x (45 - 5 x 7 + 2) ÷ 4 + 8
17 (Inside: 45 - 35 + 2 = 12. Outside: 3 x 12 ÷ 4 + 8 = 17)
What is the very first step to solve 50 - [10 + (2 x 3)]?
The inner parentheses (2 x 3)
Solve: 30 ÷ 5 x 2 + 4
16 (30 ÷ 5 = 6, then 6 x 2 = 12, then 12 + 4 = 16)
Solve: 50 - 5 x (2 + 3)
25 (2 + 3 = 5, then 5 x 5 = 25, then 50 - 25 = 25)
Find the correct value of 8 + 12 ÷ 4. Did student A get it right with 5 (8 + 12 = 20, 20 ÷ 4 = 5) or student B with 11 (12 ÷ 4 = 3, 8 + 3 = 11)?
Student B is correct (11) because division comes before addition.
Solve: 8 x (42 ÷ 7 + 15 - 9) + 12 - 20
88 (Inside: 6 + 15 - 9 = 12. Outside: 8 x 12 + 12 - 20 = 88)