1. Starter If 4 oranges cost $3.60, how much will nine oranges cost.
1 orange 90 cents
9 oranges $8.10
It takes 5 men 4 hours to chop up some firewood. How long would it take two men?
1 man 20 hours
2 men 10 hours

2. Starter
In a duck egg the ratio of yolk weight to egg-white weight is 3:2. If the egg-white weighs 14g, calculate the weight of the yolk.
Yolk = 21g
The ratio of weight lifted to their own body weight for a male Olympic-class weightlifter can sometimes exceed 5:2. If a weightlifter weighs 80kg, what weight would he aim to exceed?
Aim to lift 200kg

3. Note 9: Significant Figures
The number of significant figures a number has, is the total number of digits that represent it.
Example: (4 sf)

4. Zeros are significant when they are: inbetween other numbers
both at the end of a number and after the decimal point
Examples:
7.40
(4 sf)
(3 sf)
Zeros are not significant when they are:
at the front of a number
at the end of a number with no decimal point
Examples:
(2 sf)
(2 sf)

5. Note 10: Rounding
To round a number to a given number of decimal places/significant figures:
Underline the number of decimal place/significant figures required
Look at the next digit, if it is
less than 5, drop all numbers not underlined
5 or more, then add one to the last digit underlined and drop all other numbers
For significant figures, zeros may be needed as place holders

6. Examples: 3.8194 (2 dp) 4368 (2 sf) 12.895 (2 dp) 0.0546 (1 sf) (3.82)
Examples: (2 dp)
4368 (2 sf)
(2 dp)
(1 sf)
(3.82)
(4400)
(12.90)
(0.05)

7. Note 11: Standard Form
Very large and very small numbers are written in standard from.
Example: × 102

8. Standard Form Number
 Move the decimal point to the right if the power is positive and to the left if the power is negative.
Examples: × 102
2.46 × 10-1
536.4
0.246
Number Standard Form
Move the decimal place to after the first significant figure. Find the value of the power.
Examples:
5.812 × 103
1.9 × 10-2

9. Page 25
Exercise P
Page 27
Exercise R and S