# Percent change: Know the formula

**Here’s a question** I posed to some college students recently:

*Let’s say you cover the Town of East Middleburgtown. The mayor announces that this year’s town budget comes in at $12.6 million. Last year’s budget was $11.4 million. What is the percent change? Better yet, what’s the formula for figuring it out?*

If you don’t know the answer, or how to obtain it, you’re not alone. This kind of problem — which is in my son’s 7th grade math textbook — routinely stumps most journalists in most of the newsrooms across America.

I’ll avoid the temptation to moralize here. If you’re a journalist — if you have a pulse — you need to know this very basic operation. With it, you’ll have the power to analyze all kinds of data and even double-check the mayor’s math.

Here it is:

`(the_new_number - the_original_number) / the_original_number`

or, in the case of East Middletownburg:

`(12.6-11.4) / 11.4`

Remember (and you learned this in fifth grade) that operations in parentheses come first. That gives you this:

`1.2 / 11.4 = .105 = 10.5%`

So, the mayor’s new budget is a 10.5% increase over last year’s. Now you have something to write about!