Rounding Understand how to round numbers to the

Rounding Understand how to round numbers to the nearest 10, whole number or decimal place.

Starter – order decimals Which value is the bigger? 4. 17 km 0. 84 0. 325 0. 345 0. 72 11. 7 7. 30 cm 11. 57 7. 03 cm 4. 162 km

Starter – order decimals Put these in order, smallest first. 0. 231 3 1 2. 0 0. 132 0. 12 3 0. 312

What is the value… 3 4 5

Round the following number to 1 dp 6. 348 Firstly, highlight the number to the first number after the decimal point So we have 6. 3 But is the answer? If this. Now number look is at a 0, 1, the 2, number 3 or 4 we don’t immediately have to doafter anything where else we andstopped we havehighlighting our answer.

Round the following number to 1 dp 6. 348 = 6. 3 (1 dp)

What if the red number was a 5, 6, 7, 8 or 9? Lets look at an example

Round the following number to 1 dp If this. Now number look is at a 5, 6, the 7, number 8 or 9 we increase immediately the last digit afterby where one. we stopped highlighting 9. 2721 Firstly, highlight the number to the first number after the decimal point So we have 9. 2 But is the answer? So 9. 2 becomes 9. 3

Round the following number to 1 dp 9. 2721 = 9. 3 (1 dp)

Rounding to the nearest whole number • Is the arrow nearer to 6, 7 or 8? • If it is halfway between, then round UP 6 7 8

Round these city populations to the nearest million • Mexico City • Sao Paulo • Tokyo • New York 21. 5 million 19. 9 million 19. 5 million 15. 7 million

Rounding to the nearest 10 • Is the arrow nearer to 20, 30 or 40? • If it is halfway between, then round UP 20 30 40

What is the volume of liquid to the nearest 10 millilitres 100 90 80 70 60 50 40 30 20 10 ml

Rounding to the nearest 100 • Is the arrow nearer to 400 or 500? • If it is halfway between, then round UP 400 500

What is the mass of flour to the nearest 100 g? flour 200 400 0 600 grams • Estimate the value to the nearest 10 g

Rounding to 1 decimal place • What value is the arrow pointing at? • Is it nearer to 1. 4 or 1. 5? 1. 4 1. 5

Rounding heights & distances Women’s events • Round each of these winning heights & High Jump 2. 09 m distances to the nearest whole number Long Jump 7. 48 m • Round them to one decimal place (1 d. p. ) Shot-put 21. 95 m Discus 76. 80 m Javelin 80. 00 m

Take Care! • Round 3. 48 to 1 d. p 3. 5 • Round 3. 48 to the nearest whole number 3 (not 4)