What you’ll learn
Calculate percent decrease.
Key idea
Subtract the new amount from the original to find the decrease, divide by the original, and multiply by 100 percent. This keeps the comparison anchored to what was there before the decrease.
If a price falls from $80 to $60, it decreases by $20. Since 20 is one-fourth of the original 80, the decrease is 25%. The new amount is 75% of the original, which is different from the percent decrease.
Worked example
Enter the exact value or ordered values in the format requested below.
A price falls from $40 to $38. Enter the numerical percent decrease relative to its original price; omit the percent sign.
- The decrease is 40-38=2 dollars.
- Use the original reference: 2/40×100=5 percent; final=(1-5/100)×original.
Answer: 5
Quick Check
Evaluate a worked attempt at calculate percent decrease, identify the first invalid step, and provide the correction.
A student finds decrease from $60 to $27: Step 1, change=$33. Step 2, rate=(33/27)×100=1100/9%, using the final base. Locate the first invalid step and correct the percent.