Module 7: Working with order of operations
Performing Two or More Operations on Whole Numbers without Exponents and Grouping Symbols
Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?
Yesteday, today and tomorrow
Determine the order of operations in each mathematical expression. Write A for Addition, S for Subtraction, M for Multiplication, and D for Division.
8+4÷2
12+8-8
9x54÷6
Agnes got sick and was absent from school for a week. When she returned, she tried working on a task posed by her teacher. The task and her solution are shown below.
8 – 5 + 4 x 7 ÷ 2
= 3 + 4 x 7 ÷ 2
= 7 x 7 ÷ 2
= 49 ÷ 2
= 24.5
Is Agnes’ answer correct? Why or why not?
It is important to follow a rule when performing two or more operations on whole numbers.
Without this rule, we might calculate them in the wrong order and get a wrong answer.
Do you still remember the MDAS?
Let us use this rule to check Agnes’ solution.
M
MULTIPLY
D
DIVIDE
A
ADD
S
SUBTRACT
M
4X7=28
D
28÷2=14
S
8-5=3
A
3+14=17
8 – 5 + 4 x 7 ÷ 2
from left to right multiply or divide whichever comes first.
from left to right add or subtract whichever comes first.
______1. 48 ÷ 12 x 8
______2. 40 – 15 + 4 x 5
______3. 8 + 8 ÷ 8 x 8 – 8
______4. 20 – 18 ÷ 3 + 7
______5. 16 ÷ 4 x 5 + 7 - 8
D,M
M,S,A
D,M,A,S
D,S,A
D,M,A,S
16 ÷ 4 x 5 + 7 - 8
5 - 3 + 4 ÷ 2 x 1
20 ÷ 2 x 3 + 4 - 5
Identify the order of operations to be performed in each expression. Write A for Addition, S for Subtraction, M for Multiplication, and D for Division.
Equation | MDAS | Answer |
6 ÷ 2 + 1 x 4 | D, M, A | 7 |
| | |
2. 4 X 3 – 10 + 16 | | |
3. 3 X 3 + 10 - 3 | | |
4. 30 ÷ 2 X 4 – 8 + 9 | | |
5. 16 – 7 + 8 | | |
D,S,A
M,S,A
M,A,S
D,M,S,A
S,A
24.67
18
16
61
17
Evaluate the following expressions. Write your answers on your answer sheet.
1) 15 + 3 – 7 =
2) 8 + 8 ÷ 4=
3) 75 ÷ 5 + 9 =
4) 20 – 4 + 6 x 3 =
5) 6 ÷ 3 + 10 × 3 =
11
10
24
34
32