Word Stuff
What acronym do we use to help us remember the order of operations?
BEDMAS
9 - 3 x 2=12
Correct answer is 3. Do x then -, not - then x.
3 + 4 x 5
23
14 - 2 x 7
0
At the beginning of the day, our Grade 7 class had 16 students present. At first recess 3 students arrived and after lunch 1 student went home. Use an expression to model how many students were present at the end of the day.
16 + 3 - 1
= 19 - 1
= 18
There were 18 students present at the end of the day
Why are order of operations important for mathematicians?
So everyone can solve every problem the same (correct) way.
5 + 1 x 5 = 30
multiplication needs to be done before addition
1 x 5 = 5
5 + 5 = 10
7 + (2 x 4) - 1
14
49 ÷ (3+4) x 5
35
Mike went to the corner store with 20 dollars. He bought 5 bags of candy for $2.25 each and 3 bags of chips for $1.25. Use an expression to model how much change Mike received.
20 - (5 x 2.25 + 3 x 1.25)
= 20 - (11.25 + 3 x 1.25)
= 20 - (11.25 + 3.75)
= 20 - 15
= 5
Mike would receive $5 in change
What are the order of operations?
Brackets, Exponents, Multiplication OR Division, Addition OR Subtraction
11 - 3 x 3 +1 = 22
11 - 3 x 3 +1
11 - 9 + 1
2 + 1 = 3
56 ÷ (4+4) + 3
10
5 + 14 ÷ 2 × 5
40
Harriet went to the market on a Saturday morning with $50. She bought 5 bags of vegetables for $2.75 each, 2 bunches of flowers for $10.75 each. On the way out she bought lunch for $14.25, but luckily on her way to her car she found $10 on the ground. Use an expression to model how much money Harriet has after leaving the market.
50 - (5 x 2.75 + 2 x 10.75 + 14.25) + 10
= 50 - (13.75 + 21.50 + 14.25) + 10
= 50 - 49.50 + 10
= 0.50 + 10
= 10.50
Harriet will have $10.50 left over after her trip to the market.What should I solve first? Addition or Subtraction?
15 - 2 + 8
Why?
Subtraction because even though it is listed after Addition in the order of operations we solve addition and subtraction questions in the order they occur from left to right.
4 + 5 + 7 - 3 x 2 = 26
You need to follow BEMDAS and do x first. Correct answer is 10.
20 – (5+3) x 2 + 4
8
(4 - 1) + (5 x 1) + 9
17
Mary is going on a shopping spree with $200. She buys 2 T-Shirts for $12.75 each, 3 pairs of shorts for $30 each and a pair of sandals that were 50% off their original price of $105. Use an expression to model how much money Mary will have after her shopping spree.
200 - (2 x 12.75 + 3 x 30 + 105 / 2)
= 200 - (25.5 + 90 + 52.50)
= 200 - (115.5 + 52.50)
= 200 - 168
= 32
Mary will have $32 left over after her shopping spree
The problem was 20 - 5 x 2 + 3. My answer was 33. What did I do wrong?
I went from left to right without using the correct order of operations.
10 x 3 + (2 x 8) = 190
Follow BEDMAS
multiplication comes before addition
(5 x 4) – 6 ÷ 2 + 9
26
2 x (3 x 5) + 10 - 5
35
Mr. Parkinson went to Tim Hortons on his way to school. He bought 21 hot chocolates for $1.55 and 2 packages of tidbits for $4.75 each. He had a 5 dollar gift card and paid the rest with $40 cash. Use an expression to model how much change he will receive after paying with his cash.
20 - (21 x 1.55 + 2 x 4.75 - 5)
= 40 - (32.55 + 2 x 4.75 - 5)
= 40 - (32.55 + 9.5 - 5)
= 40 - (42.05 - 5)
= 40 - 37.05
= 2.95
Mr. Parkinson will received $2.95 in change