What you’ll learn
Calculate percent increase.
Key idea
First subtract original from new to find the increase. Then divide that difference by the original amount and multiply by 100 percent. The original is the reference whole because it is the amount before the change.
For an increase from 40 to 50, the change is 10 and the reference amount is 40. The increase is 10/40 = 1/4 = 25%. Do not divide by the new amount; that answers a different comparison.
Worked example
Enter the exact value or ordered values in the format requested below.
A price rises from $40 to $42. Enter its numerical percent increase using the original base; omit the percent sign.
- The increase is 42-40=2 dollars.
- Compare with the original base: 2/40×100=5 percent; final=(1+5/100)×original.
Answer: 5
Quick Check
Evaluate a worked attempt at calculate percent increase, identify the first invalid step, and provide the correction.
A student finds increase from $60 to $93: Step 1, change=$33. Step 2, rate=(33/93)×100=1100/31%, using the final base. Locate the first invalid step and correct the percent.