1. BIDMAS – 4 – Demonstration
This resource provides animated demonstrations of the mathematical method.
Check animations and delete slides not needed for your class.
2. 3 + 2 × 5
= 25
= 13
Who do you think is correct?
3. 3 + 2 × 5
= 25
Correct for earth!
Correct for
the alien!
= 13
Who do you think is correct?
4. = 13
We have two operations in this calculation.
Add
Multiply
According to our maths rules, we must multiply before adding.
3 + 2 × 5
3 + 10
13
Over hundreds of years rules developed
to make sure mathematics was
understood by everyone.
5. Alien rule: Add first, multiply second. Earth rule: Multiply first, add second.
Find the answer for each calculation using the alien rule, and the earth rule.
4 + 3 × 2 10
14
5 × 5 + 2 27
35
3 + 2 × 4 11
20
2 × 6 − 5 7
2
8 − 4 ÷ 2 6
2
6. 8 − 3 + 2 − 1
Change the order of operations for these calculations.
How many different results can you find?
When is the order of operations most important?
4 × 8 ÷ 2
5 + 2 × 3
4 × 3 − 2
6 + 8 − 4
24 ÷ 8 − 2
= 6 = 16
= 21
= 11
= 4
= 10 = 1
= 4
= 10
7. Only two of these calculations give the correct answer.
Can you work out the order of operations?
3 4
5
3 + 4 × 5 (3 + 4) × 5
5 × 3 + 5 × 4
8. The order of operations tells us their priority.
( )
1st Brackets
42
2nd Indices
÷ ×
3rd Division & Multiplication
+ −
4th Addition & Subtraction
helps us remember!
9. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
6 + 5 × 3 =
6 + 15 = 21
Bracket the
priority
calculation.
Calculate bracket
& rewrite.
( )
10. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
4 + 2 × 6 =
4 + 12 = 16
Bracket the
priority
calculation.
Calculate bracket
& rewrite.
( )
11. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
4 × 3 − 7 =
12 − 7 = 5
Bracket the
priority
calculation.
Calculate bracket
& rewrite.
( )
12. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
6 + 15 ÷ 5 =
6 + 3 = 9
Bracket the
priority
calculation.
Calculate bracket
& rewrite.
( )
13. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
(8 + 6) ÷ 2 =
14 ÷ 2 = 7
Calculate bracket
& rewrite.
14. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
10 ÷ 2 − 2 =
5 − 2 = 3
Bracket the
priority
calculation.
Calculate bracket
& rewrite.
( )
15. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
4 × 3 − 5 × 2 =
12 − 10 = 2
Bracket the
priority
calculations.
Calculate bracket
& rewrite.
( ) ( )
16. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
8 + 7 × 2 − 6 =
8 + 14 − 6 = 16
Bracket the
priority
calculations.
Calculate bracket
& rewrite.
( )
17. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
Bracket the
priority
calculations.
Calculate bracket
& rewrite.
Copy & complete these sums.
2 × 4 + 3 = 11
6 + 5 × 2 = 16
(5 + 2) × 4 = 28
(3 + 2) × (8 ÷ 4) = 10
6 + 4 × 4 − 2 = 20
7 + 12 ÷ 3 + 5 = 16
6 + 4 × 3 ÷ 2 = 12
20 ÷ 4 × 2 + 8 = 18
12 − 2 ÷ 5 − 1 = 1
6 + 2 × 3 + 9 ÷ 3 = 15
A
B
C
D
E
F
G
H
I
J
18. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
Calculate bracket
& rewrite.
Copy & complete these sums.
2 × 4 + 3 = 11
6 + 5 × 2 = 16
(5 + 2) × 4 = 28
(3 + 2) × (8 ÷ 4) = 10
6 + 4 × 4 − 2 = 20
7 + 12 ÷ 3 + 5 = 16
6 + 4 × 3 ÷ 2 = 12
20 ÷ 4 × 2 + 8 = 18
12 − 2 ÷ 5 − 1 = 1
6 + 2 × 3 + 9 ÷ 3 = 15
A
B
C
D
E
F
G
H
I
J
Bracket the
priority
calculations.
19. Calculations on the inside.
( )
Left to right
÷ ×
Left to right
+ −
Calculate bracket
& rewrite.
Copy & complete these sums.
2 × 4 + 3 = 11
6 + 5 × 2 = 16
(5 + 2) × 4 = 28
(3 + 2) × (8 ÷ 4) = 10
6 + 4 × 4 − 2 = 20
7 + 12 ÷ 3 + 5 = 16
6 + 4 × 3 ÷ 2 = 12
20 ÷ 4 × 2 + 8 = 18
12 − 2 ÷ 5 − 1 = 1
6 + 2 × 3 + 9 ÷ 3 = 15
A
B
C
D
E
F
G
H
I
J
Bracket the
priority
calculations.
