Starter

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. Note 9: Significant Figures The number of significant figures a number has, is the total number of digits that represent it. Example:3147 (4 sf)

3. Zeros are significant when they are: • inbetween other numbers • both at the end of a number and after the decimal point • Examples: 9.703 • 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:0.036 24000 (2 sf) (2 sf)

4. 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

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

6. Page 25 Exercise P Page 22 Exercise N and O