You won’t see too much content here at Green Caret about math. Like many writers and editors, I am unapologetically a word person. But (perhaps unlike many writers and editors) I also enjoy working with numbers, and — thanks to an accountant father who trained me early — I can rock a ten-key better than most.

Basic math skills come in handy in my line of work more often than you might think. Consider the following passage:

The 56 survey respondents were not representative of the community, where Native Americans and Blacks each make up one-third of the population. The majority of respondents were Caucasian, with only 0.89% Black and 0.017% Native American. Future studies should include efforts to increase diversity in the survey sample.

If there’s one lesson I learned from doing story problems throughout my educational career, it’s this: Even if your computations seem accurate, look at your final answer and ask, “Does it make sense?” When we apply that common-sense test to the figures in the example, things don’t quite add up.

For example, take a look the figure 0.89%. That’s less than 1%, and 1% means one person out of 100. However, this survey had only 56 respondents, so 0.89% translates to less than one person here! Something is clearly amiss.

Let’s back up and redo the math, dividing integers by 56. Rounding to three places, we get these results:

1 ÷ 56 = 0.017
2 ÷ 56 = 0.035
3 ÷ 56 = 0.054
4 ÷ 56 = 0.071
5 ÷ 56 = 0.089

Any of those numbers look familiar? Sure they do. It looks like the writer got a little confused with moving the decimal point. And hey, there’s no shame in that: it’s been a long time since any of us first learned about percentages.

Remember that 100% equals one (or 1.00). So to convert from a fraction to a percentage, you move the decimal two places to the right.

1 ÷ 56 = 0.017 = 1.7%
2 ÷ 56 = 0.035 = 3.5%
3 ÷ 56 = 0.054 = 5.4%
4 ÷ 56 = 0.071 = 7.1%
5 ÷ 56 = 0.089 = 8.9%

Percentages are always bigger than decimals — that’s why we use them, because whole numbers are easier to grasp than fractions.

With that in mind, let’s look at what’s most helpful to the reader here. With only 56 people in the group we’re talking about, it probably makes sense to talk about the actual number of respondents, especially when it comes to a single Native American individual. (Isn’t it kind of ridiculous to say that the group is 1.7% Native American when that 1.7% equals one person?) However, it’s still important to include the percentages, because the writer is making a comparison with the racial make-up of the community.

Here’s where I ended up with the passage:

The 56 survey respondents were not representative of the community, where Native Americans and Blacks each make up one-third of the population. The majority of respondents were Caucasian, with only five Black (8.9%) and one Native American (1.7%). Future studies should include efforts to increase diversity in the survey sample.

Better, right? Not only are the numbers now accurate, but they also work a little harder for the reader.

Who says all those story problems you did were good for nothing?

Advertisements