ACT Preparation / Unit 7 ACT 0628 short lesson, about 20 seconds
Percent Change: Divide by the Original
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The idea
Percent change is the amount of change divided by the original amount. An increase gives a percent increase; a decrease, a percent decrease.
In practice
A price rising from $40 to $50 changes by $10; 10 ÷ 40 = 25%.
Where people slip
Divide by the original, never the new amount: 10 ÷ 50 = 20% answers a different question, the decrease from 50 back to 40.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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