Fractions - the four rules

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Fractions - the four rules

  1. 1. FRACTIONS <ul><li>This presentation will help you to add, subtract, multiply and divide fractions. </li></ul>Left click on the mouse to reveal the next section
  2. 2. To learn about: Adding fractions click Subtracting fractions click Dividing fractions click Multiplying fractions click
  3. 3. Adding fractions <ul><li>To add fractions together the denominator (the bottom bit) must be the same. </li></ul><ul><li>Example </li></ul>
  4. 4. Now try these <ul><li>Click on the mouse to reveal the answers. </li></ul><ul><li>1 . 2 . </li></ul><ul><li>3 . 4 . </li></ul>
  5. 5. Subtracting fractions To subtract fractions the denominator (the bottom bit) must be the same. Example
  6. 6. Now try these Click on the mouse to reveal the answers. 1 . 2 . 3 . 4 .
  7. 7. Multiplying fractions To multiply fractions we multiply the tops and multiply the bottoms Top x Top Bottom x Bottom
  8. 8. Multiplying fractions Example
  9. 9. Now try these Click on the mouse to reveal the answers. 1 . 2 . 3 . 4 .
  10. 10. Dividing fractions Once you know a simple trick, dividing is as easy as multiplying! <ul><li>Turn the second fraction upside down </li></ul><ul><li>Change the divide to multiply </li></ul><ul><li>Then multiply! </li></ul>
  11. 11. Dividing fractions <ul><li>Turn the second fraction upside down </li></ul>Example <ul><li>Change the divide into a multiply </li></ul><ul><li>Then multiply </li></ul>
  12. 12. Now try these Click on the mouse to reveal the answers. 1 . 2 . 3 . 4 .
  13. 13. Common denominators <ul><li>To add or subtract fractions together the denominator (the bottom bit) must be the same. </li></ul>So, sometimes we have to change the bottoms to make them the same. In “maths-speak” we say we must get common denominators
  14. 14. Common denominators <ul><li>To get a common denominator we have to: </li></ul>1. Multiply the bottoms together. 2. Then multiply the top bit by the correct number to get an equivalent fraction
  15. 15. Common denominators <ul><li>For example </li></ul><ul><li>Multiply the bottoms together </li></ul>
  16. 16. Common denominators <ul><li>For example </li></ul>2. Write the two fractions as sixths
  17. 17. Common denominators <ul><li>For example </li></ul>To get ½ into sixths we have multiplied the bottom (2) by 3. To get an equivalent fraction we need to multiply the top by 3 also
  18. 18. Common denominators <ul><li>For example </li></ul>To get 1/3 into sixths we have multiplied the bottom (3) by 2. To get an equivalent fraction we need to multiply the top by 2 also
  19. 19. Common denominators <ul><li>For example </li></ul>We can now rewrite
  20. 20. Common denominators This is what we have done: 1. Multiply the bottoms 2.Cross multiply
  21. 21. Now try these Click on the mouse to reveal the answers. 1 . 2 . 3 . 4 .
  22. 22. For further info <ul><li>Go to: </li></ul><ul><li>BBC Bitesize Maths Revision site </li></ul><ul><li>by clicking here: </li></ul>

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