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Fractions in Disguise

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A shop card says 20% OFF. Off what?

Figure 1 — a percentage marks one point on a fixed 0-to-100 scale.

This track follows Part II, Chapter 1, Fractions in Disguise.

What you will learn

  • Out of a hundred — the second number is always 100.
  • Three names — a fraction, a decimal and a percentage.
  • Taking a percentage — how much is 15% of 200?
  • Finding a percentage — 18 out of 24 is what percentage?
  • Up and down — a rise or a fall is of the start. You can also find the start.
  • There and back — up 20%, then down 20%.
  • Comparing fairly — two groups, one fair number.
  • Where they are used — a target, a marked price, a total.

Every lesson has a lab. Move something and watch the percentage.

Need a quick recap?

  • Fractions (Class 6) — the bottom number sizes one part.
  • Hundredths (Class 7) — 0.01 is one hundredth.

Jump to lesson

This track

  1. 0 Start here
  2. 1 A comparison with a hundred underneath
  3. 2 Three names for one amount
  4. 3 Taking a percentage of an amount
  5. 4 One amount said as a percentage of another
  6. 5 Measured against what you started with
  7. 6 An equal rise and fall do not cancel
  8. 7 Comparing two groups of different sizes
  9. 8 Where percentages are used
  10. 9 The big picture
  11. 10 Track quiz

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