Find the Percent Change

Finn reads this

Percent change is the change compared with the original amount. Find the change, then ask what percent of the start it is.

A game drops in price

Finn reads this

A game drops from $50 to $35. The change is $50 minus $35, which is $15. Then: 15 out of 50. That is 0.30, which is 30 percent. The price went down, so it is a 30 percent decrease.

Divide by the original

Elle reads this

The rule, and the place people slip: always divide the change by the original amount, never by the new amount. $15 out of the original $50 is 30 percent. $15 out of the new $35 would be about 43 percent, and that is not what percent change means.

ElleMath-speak

Percent change equals the change divided by the original amount, written as a percent.

FinnPlain English

Find how much it changed, then ask: what percent of the start is that?

An increase on the bar

Finn reads this

A plant grows from 40 centimeters to 50 centimeters. The change is 10. Ten out of 40 is one fourth, which is 25 percent. A 25 percent increase. On the bar, the new amount runs past the end of the original.

Let me try a few

NC standards: NC.7.RP.3.

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