Percentages: watch it solved step by step

A percentage of an amount, increase and decrease, percentage change and finding the whole, each with a check. Level: KS3 / GCSE. Type any problem of this kind and the Lab works it out and animates every move, with a plain-words explanation of why.

Worked example: increase 80 by 15%

  1. The question. Make 80 bigger by 15% of itself.
  2. Find the percentage of the amount. First work out the size of the change: the percentage of the original amount.
  3. Add it on. An increase is added to the original amount.
  4. A one-step shortcut. Multiplying by 2320 does the same in one go: 100% + 15% = 115% of the original.

Answer: 92

Practise percentages with problems the Lab marks for you.

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