### Chap 2: Real Numbers - Spot the Common Mistakes (I)

Revision Exercise 2 (p52 of Textbook) No. 7(a)

1. (-16) x (-3) - (-8) x 5
= 48-(-40)
=88

2. (-16)x(-3)-(-8)x5
=48-(-40)
=88

3. (-16)X(-3)-(-8)X5
=48--40
=88

Ziying

4. (-16)x(-3)-(-8)x5= 48-(-40)
=88

5. (-16) x (-3) - (-8) x 5
=48 - (-8) x 5
=48 + 8 x 5
=48 + 40
=88

6. (-16) x (-3) - (-8) x 5=48 + (8 x 5)
=48 + 40
=88

7. (-16)x(-3)-(-8)x5=48-(-40)
=48+40
=88

8. The sum sentence should be 48--40 but the person took it as 48-40

Note that -8X5 is -40 so there is an extra negative sign

9. (-16)x(-3)-(-8)x5
=48+40
=88
Ans: 88

10. (-16)x(-3) - (-8) x 5
=48 - (-40)
=88

11. (-16)x(-3)-(-8)x5
= 48-(40)
=88

12. It should have been:
(-16) X (-3) - (-8) X 5
= 48 - (-8) X 5
= 48 + 40
= 88

The mistake was 48 - 40 when it should actually be 48 + 40.

13. (-16) x (-3) - (-8) x 5
= 48 -(-40)
= 88

chengngee

14. (-16)x(-3)=48
(-8)x5=(-40)
48-(-40)=88
Ans:88

15. (-16)x(-3)-(-8)x5
=48-(-40)
=48+40
=88

16. (-16)x(-3)-(-8)x5
=48-(-40)
=48+40
=88
He should do multiplication first before subtraction.

17. (-16)x(-3)-(-8)x5
=48-(-40)
=48+40
=88

18. (-16) x (-3) - (-8) x 5
=48-(-40)
=48+40
=88

19. (-16)x(-3)-(-8)x5
=48-(-40)
=88

20. (-16) x (-3) - (-8) x 5
= 48 - (-8) x 5
= 48 - (-40 )
= 48 + 40
= 88

21. (-16)x(-3)-(-8)x5
=48-(-40)
=88

22. Class S1-01

Well done... all correct...

when we have 2 signs side by sign to each other,
e.g. 48--40, we'll need to separate them with a bracket so that it looks like
48 - (-48)

If need to shown working for each group,
e.g.
(-16)x(-3)=48
(-8)x5=(-40)

Good to leave some space above and below so that the reader will note that this is working of smaller groups of number.
Alternatively, can write them by the side (when working is to be done on paper).

:D