1. Significant Figures
Significant figures are those numbers considered to be important in value All non-zero digits are significant Zeros are NOT always significant
To compare two numbers you would need the 3
To compare two numbers for 203 the 0 plays an important role

2. Significant Figures
The first significant figure is always the first non-zero digit you come across
(from left to right)

3. To Round to Significant Figures
Identify the significant figure
Look at the number next to it
Round up or down
All the numbers AFTER will become ZERO

4. There were 64,492 people at a football match
Round 64,492 to
1 significant figure
60,000
Round 64,492 to
2 significant figures
64,000
Round 64,492 to
3 significant figures
64,500
Round 64,492 to
4 significant figures
64,490

5. Rounding to 1 s.f. means in the answer we should have 1 significant figure
Rounding to 2 s.f. means in the answer we should have 2 significant figures
Rounding to 3 s.f. means in the answer we should have 3 significant figures

6. It’s more than 4 so we round up!
Round to 1 s.f. 3 7 8 5 4 3 7
Look at the next number
It’s more than 4 so we round up!

7. It’s less than 5 so we round down!
Round to 3 s.f. 3 7 8 4 3 7
Look at the next number
It’s less than 5 so we round down!

8. It’s more than 4 so we round up!
Round to 2 s.f. . 2 9 8 9
Look at the next number
It’s more than 4 so we round up!

9. It’s more than 4 so we round up!
Round to 3 s.f. . 2 9 8 7
Look at the next number
It’s more than 4 so we round up!

10. Rounding to significant figures
Complete this table:
to 1 s.f.
to 2 s.f.
to 3 s.f.
6.3528
34.026
850951

11. Rounding to significant figures
Complete this table:
to 1 s.f.
to 2 s.f.
to 3 s.f.
6.3528 6
6.4
6.35
34.026 30 34
34.0
0.006
0.0057
200
150
151

12. Pg _____ Exercise 1G No.s 38 - 47
Homework
Pg _____ Exercise 1G No.s