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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.
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Rounding Understand how to round numbers to the nearest 10, whole number or decimal place.
Starter – order decimals Which value is the bigger? 4.17km 0.84 0.325 0.345 0.72 11.7 7.30cm 11.57 7.03cm 4.162km
Starter – order decimals Put these in order, smallest first. 0.231 0.213 0.132 0.123 0.312
What is the value… 3 4 5
Round the following number to 1dp 6.348 If this number is a 0, 1, 2, 3 or 4 we don’t have to do anything else and we have our answer. Now look at the number immediately after where we stopped highlighting Firstly, highlight the number to the first number after the decimal point So we have 6.3 But is this the answer?
Round the following number to 1dp 6.348 = 6.3 (1dp)
What if the red number was a 5, 6, 7, 8 or 9? Lets look at an example
Round the following number to 1dp 9.2721 If this number is a 5, 6, 7, 8 or 9 we increase the last digit by one. Now look at the number immediately after where we stopped highlighting Firstly, highlight the number to the first number after the decimal point So we have 9.2 But is this the answer? So 9.2 becomes 9.3
Round the following number to 1dp 9.2721 = 9.3 (1dp)
Roundingto 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 21.5 million • Sao Paulo 19.9 million • Tokyo 19.5 million • New York 15.7 million
Roundingto the nearest 10 • Is the arrow nearer to 20, 30 or 40? • If it is halfway between, then round UP 20 30 40
100 90 80 70 60 50 40 30 20 10ml What is the volume of liquid to the nearest 10 millilitres
Roundingto the nearest 100 • Is the arrow nearer to 400 or 500? • If it is halfway between, then round UP 400 500
flour 200 400 0 600 grams What is the mass of flour to the nearest 100g? • Estimate the value to the nearest 10g
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 • Round each of these winning heights & distances to the nearest whole number • Round them to one decimal place (1 d.p.)
Take Care! • Round 3.48 to 1 d.p 3.5 • Round 3.48 to the nearest whole number 3 (not 4)