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PEAZIT Aha card

Percentages: always ask “of what?”

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When the base changes, the same percentage means a different amount.

First +20%, then −20% of the new value.
BaseChangeResult
100+20% = +20120
120−20% = −2496

One worked example

  1. 100 × 1.20 = 120After the increase, you have 120% of the original value.
  2. 120 × 0.80 = 96After the decrease, you have 80% of the new value.

Watch out: Percentage change and percentage-point difference are different. Check whether the original or new base is intended.

Goal, prerequisites and card origin

What you will learn: Calculate two percentage changes with changing bases.

What you need first: A percent is one hundredth; multiplying decimals.

An original PEAZIT working card. Independent expert review and effectiveness testing have not yet taken place. · v1

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When the base changes, the same percentage means a different amount.

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