1. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To remind how to round to a given number of significant figures. Objectives

2. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Remember that all rounded answers must still be roughly the same size as your original, unrounded number................and this often means that you need to replace several digits with zeros!

3. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. How do we know which figures are significant? 45640 The first most significant figure is..........the first non-zero digit when reading from the left. 1st 3rd2nd4th Zeros become significant after the first significant figure.

4. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. How do we know which figures are significant? 0.0004567 1st None of the zeros before the 4 are significant.

5. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 0.000045801 to 2 significant figures..... 0.00004580 You don’t change any significant figures before the second. 4

6. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 0.000045801 to 2 significant figures..... 0.00004580 4 If the next digit after your second is five or more, round up 6

7. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 0.000045801 to 2 significant figures..... 0.00004580 Then replace digits with zeros to ensure that the new number is roughly the same size as the old one. 46

8. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 0.000045801 to 2 significant figures..... 0.00004580 And zeros after the 6 will not change the value. Leave these out. 460.0000

9. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 4560794 to 3 significant figures..... 4560794 45 unchanged If the digit after the 3 rd most significant figure is less than 5, leave the 6 alone. 6 also unchanged

10. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To round 4560794 to 3 significant figures..... 4560794 45 unchanged 6 also unchanged Put zeros on the end to make the answer the right size. 0000