What is the formula to calculate the percentage change between Old and New values?

• A. (New - Old) / Old × 100
• B. (Old - New) / Old × 100
• C. (New - Old) / New × 100
• D. Old / New × 100

Answer: (A)

Percent change tells you how much a quantity has shifted compared to its starting value. The amount of change is New minus Old, and to express that change as a percentage you divide by the original value (Old) and multiply by 100. This uses the starting point as the reference, so increases and decreases are measured relative to where you began.

For example, if Old is 50 and New is 60, the change is 10. Then 10 divided by 50 equals 0.2, and times 100 gives 20%. The sign reflects direction: if New is bigger, it’s a positive percentage; if New is smaller, it’s negative.

Using the new value as the base or using Old as a ratio to New would describe a different quantity, not the standard percent change. Also, if the original value is zero, the percent change is not defined.