Order of Operations
Grade 9
2009
Order of Operations
5 + 6 x 4 = 44 or 29
Why do we need rules?
What are the rules?
BODMAS
• Brackets {(innermost first)}
• Of and Other Operations
• Division and Multiplication (working left to right
)
• Addition and Subtraction (working left to right
)
Rosemary Ngwenya
2009
Let’s do these together
a) 4 + 12 – 5 + 6
b) 4 + 12 – (5 + 6)
c) 6 + 21 ÷ 7
d) {4 x (5 + 8)} ÷ 2
Writing equations from worded problems
Mum brought 2 packets of Easter eggs to hide in the
garden for her 4 children to find. Each packet contained
20 eggs. While she was hiding them the dog ate 4
eggs, Date ate 3 and 1 was squashed. If all the other
eggs were found, and each child found the same
number of eggs, how many did each child have.
{2 x 20 – (4 + 3+ 1)} ÷ 4
Rosemary Ngwenya
2009
Some for you to try
Rosemary Ngwenya
2009
answers
Answers
44
65
94
56
36
Back
Rosemary Ngwenya
2009
Worded problems for you to try
Rosemary Ngwenya
2009
Answers
(3 x 12) ÷ {20 – (3 + 5)}
→
36 ÷ {20 – 8}
→
36 ÷ 12
3
Each class member had 3 biscuits
→
Rosemary Ngwenya
2009
Answers
Let total price paid = P
P = 100 + 2 x (100 – 25)
P = 100 + 2 x 75
P = 100 + 150
P = 250
The total price paid was $250.
Rosemary Ngwenya
2009