1. 234 + 500 – 21 420 – 632 + 324 Can you work these out? = 713 = 112
Collect Homework
Can you work these out?
= 713
– 21
420 –
= 112

2. L.O. To be able to work out mixed addition and subtraction expressions
By the end of the lesson we will be able to:
understand that the sign in front of a number tells you what to do with that number
identify when we can work out a mixed sum by going left to right
identify when we must change the order to work out a mixed sum

3. What must you remember?
You must remember that it is the sign IN FRONT of the number that tells you what to do with that number!
If the sign is plus you must add that number to the rest
If the sign is minus you must take that number away from the rest

4. You can add and take away in ANY ORDER
Example – 94
To 138 we must add 76 and take away 94
We can do the operations in any order but we MUST START WITH THE FIRST NUMBER !!!
I can add 76 first then take away 94
= 214
214 – 94 = 120
I can take away 94 first then add 76
138 – 94 = 44
= 120

5. Example: 42 –
We must start with 42 but we can add and take away in any order
Notice that we can’t take away 70 first so we must choose a different order here!
We can do the operations in any order but we MUST START WITH THE FIRST NUMBER !!!
I can add 51 then take away 3 and 70
= 93
93 – 3 = 90
90 – 70 = 20
I can take away 3 first then add 51 and take away 70
= 39
= 90
90 – 70 = 20

6. Example: 95 –
We must start with 95 but we can add and take away in any order
Notice that we can’t take away 161 first so we must choose a different order!
We can do the operations in any order but we MUST START WITH THE FIRST NUMBER !!!
I can add 75 first then take away 161 and add 10
= 170
170 – 161 = 9
= 19
I can add 10 first then 75 then take away 161
= 105
= 180
180 – 161 = 19

7. Mixed addition & subtraction
You MUST ALWAYS start with the FIRST number
To this first number you can then add or take away in any order
The sign IN FRONT of the number tells you what to do with that number

8. Suggestion..
If you can work the sum in the order that it is given, then do it !
If you can’t, then remember that the sign in front tells you what to do with the number!

9. Bingo Activity Time CHOOSE ANY 6 NUMBERS30 20 95 13
597
144 25
129 83 5 4
CHOOSE 6 NUMBERS

10. – 8 – 3
= 16
16 – 8 = 8
8 – 3 = 5
If you chose 5  cross it off!

11. 36 –
= 12
= 74
74 – 49 = 25
If you chose 25  cross it off!

12. 361 – – 81
361 – 200 = 161
= 176
176 – 81 = 95
If you chose 95  cross it off!

13. –
= 137
= 230
230 – 210 = 20
If you chose 20  cross it off!

14. – 78 – 50
= 128
128 – 78 = 50
50 – 50 = 0
If you chose 0  cross it off!

15. 23 –
= 21
= 25
25 +5 = 30
If you chose 30  cross it off!

16. 952 – 1010 –
= 1390
= 380
380 – 251 = 129
If you chose 129  cross it off!

17. – 11 – 9
= 33
33 – 11 = 22
22 – 9 = 13
If you chose 13  cross it off!

18. – 9 – 3 – 5
= 21
21 – 9 = 12
12 – 3 = 9
9 – 5 = 4
If you chose 4  cross it off!

19. If you chose 144  cross it off!
Find the difference between one hundred and ninety, and eighty-three. Then add on thirty-seven
190 – 83 = 107
= 144
If you chose 144  cross it off!

20. – 78 – 14
= 175
175 – 78 = 97
97 – 14 = 83
If you chose 83  cross it off!

21. 612 –
612 – 318 = 294
= 513
= 597
If you chose 597  cross it off!

22. L.O. To be able to work out mixed addition and subtraction expressions
By the end of the lesson we will be able to:
understand that the sign in front of a number tells you what to do with that number
identify when we can work out a mixed sum by going left to right
identify when we must change the order to work out a mixed sum

23. Homework for Tomorrow
STP 7 Pg 9 Exercise 1f
1,11,13,17,19,21,29(p10)