Starter – Premier League Attendance Write the attendance in words (don’t forget spelling!) and then round each attendance to the nearest 10, nearest 100, nearest 1000 and nearest 10000.

Answers Fifty-nine thousand, nine hundred and twelve 59910 59900 60000 Forty-four thousand, three hundred and thirty 44330 44300 44000 40000

Answers Forty-one thousand and seventy-three 41070 41100 41000 40000 Twenty-four thousand and ninety-eight 24100 24100 24000 20000

1DP 2DP 3DP 4 . 8 5 2 1 . 6 9 4 9 5 . 2 6 2 7 5 or more? 5 or more? 5 or more? Yes No Yes 4 . 9 1 . 6 9 5 . 2 6 3 Choose red, amber or green Number To 1DP To 2DP To 3DP 63.4721 87.6564 149.9875 3.54029 0.59999 63.5 63.47 63.472 87.7 87.66 87.656 Your Turn 150.0 149.99 149.988 3.5 3.54 3.540 0.6 0.60 0.600

Significant Figures If you read that the attendance at a football match was exactly 41,786 and a friend asked you about the attendance, you would probably say “about 40,000”. In this case you are giving an approximate answer to one significant figure.

Significant Figures Find the first ‘non-zero’ digit in your number – this is your first significant figure (and every digit after this is significant, even zeros). Count along the correct number of digits (same as the number of significant figures you are rounding too) and round normally. Check your answer makes sense – if you have rounded 32745 to 2 sig. figs. and got an answer of 38 that isn’t sensible. Your answers should be of a similar size to your original number.

Rounding to one significant figure: Significant Figures Rounding to one significant figure: 1 4 7 2 2 6 7 2 8 0 . 0 3 2 8 5 or bigger ? 5 or bigger ? 5 or bigger ? No No Yes 1 000 30 000 0.03

Answers Q1 (a) 3 (b) 4 (c) 1 (d) 2 (e) 4 (f) 6 Q2

This symbol means “approximately equal to” Estimate the answer to 6.32 x 9.5 When estimating, we first need to round EVERY number in the question to one significant figure. We round 6.32 to 1 s.f. 6 We round 9.5 to 1 s.f. 10 6.32 x 9.5  6 x 10 = 60 This symbol means “approximately equal to”

Sally bought 18 packets of crisps at 32p each. Estimate how much she spent When estimating, we first need to round EVERY number in the question to one significant figure. We round 18 to 1 s.f. 20 We round 32 to 1 s.f. 30 18 x 32  20 x 30 = 600p = £6.00

Billy can write 24 words a minute Billy can write 24 words a minute. Estimate how long it took him to write 643 words. When estimating, we first need to round EVERY number in the question to one significant figure. We round 24 to 1 s.f. 20 We round 643 to 1 s.f. 600 643 ÷ 24  600 ÷ 20 = 30 minutes

On a long haul flight an aeroplane flew 3123 miles in 9. 6 hours On a long haul flight an aeroplane flew 3123 miles in 9.6 hours. Work out an estimate of how many miles it flew each hour. a) 3000 b) 30 c) 300

Estimate the answer to this question. 54.6 x 2.91 ? a) 1500 b) 150 c) 15

Martyn rode 287 kilometres in 11 days Martyn rode 287 kilometres in 11 days. Roughly how many kilometres did he ride each day? a) 30 b) 300 c) 3

Estimate the answer to this question. 2.1 x 9.7 x 3.7 ? a) 80 b) 800 c) 0.8

A square has edges of length 2.14cm. What is an estimate of the area? a) 4cm² b) 40cm² c) 0.4cm²

Estimate the answer to this question. 935 x 29 ? a) 27000 b) 2700 c) 270

At a theatre they sold 73 cups of coffee during the interval at 68p a cup. Estimate the amount they took on coffee. a) £4.90 b) £490 c) £49

Estimate the answer to this question. 34.87 x 20.27 ? a) 60 b) 6 c) 600

At Dave’s ice cream stall he sold 223 ice creams at 67p each At Dave’s ice cream stall he sold 223 ice creams at 67p each. Estimate how much his takings were that day. a) £140 b) £1400 c) £14000

Estimate the answer to this question. 3.14 x 7.92 ? a) 240 b) 24 c) 0.24