Percents and Percent Change

Received via Twitter:
What % drop is 2,800,000 from 4,150,000?

THE SOLUTION:
To calculate percent change, we take this formula: and write the answer as a percentage (just move the decimal point two places to the right). If the resulting value is positive, we have a "percent increase." On the other hand, if it is negative, we call it a "percent decrease" (i.e. a "drop"). In this particular problem, the initial value is 4,150,000 and the final value is 2,800,000. Based on the way the problem is stated, this may not be obvious. The word to focus on is "from" because it tells you that you're starting at 4,150,000.

Now, if I were answering the original question, I would leave the negative value out. The problem asks for a percent drop so the negative sign is not necessary. We'd simply say, "The drop is about 32.5%."

A Note About Percentages:
"Percent" and "percent change" are two very different concepts, but people are often confused between the two. Let's say the original problem said, "What percent of 4,150,000 is 2,800,000?" You would use instead of the formula above. For this particular problem, that means .
Words like "drop", "decrease", "change" and "increase" are clues that you're dealing with percent change, whereas those involving a discount ("x percent off") or calculating one's grade are straight percentage problems.