1. L.O.1 To be able to use known facts and place value to multiply and divide mentally.

2. Answer these on your whiteboards:
What are 10 lots of 5?
What is the product of 20 and 5?
What is 30 multiplied by 5?
What are 10 lots of 6?
What is the product of 20 and 6?
What is 30 multiplied by 6?

3. As 20 is double 10
so 20 x 6 = double 10 x 6
20 x 6 = 2 x (10 x 6)
= 120

4. As 30 is treble 10
so 30 x 6 = treble 10 x 6
30 x 6 = 3 x (10 x 6)
= 180

5. As 40 is quadruple 10
so 40 x 6 = quadruple 10 x 6
40 x 6 = 4 x (10 x 6)
= 240

6. As 50 is quintuple 10
so 50 x 6 = quintuple 10 x 6
50 x 6 = 5 x (10 x 6)
= 300

7. Q. How many 6’s are there in 120?
How do you know?
120 = 12 x 10
so 120 ÷ 6 = (12 ÷ 6) x 10
= 2 x 10
= 20

8. What are the answers to these?
180 ÷ 6
240 ÷ 6
300 ÷ 6
360 ÷ 6
420 ÷ 6
480 ÷ 6
540 ÷ 6

9. LOOK…
180 ÷ 6 = (18÷6) x = 3 x = 30
240 ÷ 6 = (24÷6) x = 4 x = 40
300 ÷ 6 = (30÷6) x = 5 x = 50
360 ÷ 6 = (36÷6) x = 6 x = 60
420 ÷ 6 = (42÷6) x = 7 x = 70
480 ÷ 6 = (48÷6) x = 8 x = 80
540 ÷ 6 = (54÷6) x = 9 x = 90

10. What are the answers to these?
÷ 4
÷ 5
÷ 2
÷ 4
÷ 7
÷ 9
÷ 2
÷ 8

11. LOOK…
÷ 4 = (240÷4) = 6 x 10 = 60
÷ 5 = (250÷5) = 5 x 10 = 50
÷ 2 = (180÷2) = 9 x 10 = 90
÷ 4 = (200÷4) = 5 x 10 = 50
÷ 7 = (280÷7) = 4 x 10 = 40
÷ 9 = (540÷9) = 6 x 10 = 60
÷ 2 = (160÷2) = 8 x 10 = 80
÷ 8 = (320÷8) = 4 x 10 = 40

12. L.O.2
To be able to approximate;
extend written methods to short division of HTU by U;
estimate by approximating
then check results.

13. Q. Approximately how many fives are there in 183?
We are going to use a shorter written method for division.
183 ÷ 5
Q. Approximately how many fives are there in ?

14. 183 ÷ 5 We know that 30 x 5 = 150 We know that 40 x 5 = 200
so as 183 comes between 150 and 200
our answer lies somewhere between
30 and 40

15. 183 Using chunking… Watch carefully!
We can start by using the LOWER of our two estimates…
183
- ( 30 x 5)
150 33
- ( 6 x 5) 30 3
Answer = 36 r.3
Q. Is 36 r.3 likely to be correct? How do you know?

16. Try this on your own. When you have an
Try this on your own. When you have an answer compare it to your partner’s.
147 ÷ 6

17. There is a similar method called short division.
Our sum is 183 ÷ 5
CHUNKING SHORT DIVISION
36r.3
(30 x 5) (30 x 5)
(6 x 5) (6 x 5)
Answer = 36r.3
How are these sums similar? How are they different?

18. 1. 154 ÷ 5 Try these: Use the SHORT DIVISION method. 2. 176 ÷ 5
Approximate the answers first.
Use the LOWER multiple of the divisor as the first subtraction.
÷ 5
÷ 5
÷ 5
÷ 4
÷ 6
÷ 6

19. Answers??
÷ 5
÷ 5
÷ 5
÷ 4
÷ 6
÷ 6
Q. Do the answers seem to be correct compared to the approximations?
Check your own answers. Where have you gone wrong?

20. By the end of the lesson the children should be able to :
Use short division to divide HTU by U;
Approximate results first and use the approximation to check whether results are reasonable