Divisibility and Percent Change on the SAT

In my last post I talked about some of the very basic SAT math concepts. Today, I want to do the same thing, but make the topic a bit more complicated. Today, we are going to break through the rules of divisibility, percents, fractions, and percent change.

Students who cannot quickly convert decimals into fractions waste precious time on simple things like long division and calculation. The SAT is a timed test. You will need to be as effective and efficient as possible throughout the entire experience. If you don’t understand, there are books and tutors that you can use. It is with that understanding that we move to our lessons.

The Rules of Divisibility

The SAT test writes assume you know what makes a number divisible by another number. Briefly, a number is divisible by another number if you are able to divide it and get an integer. And integer is a whole number (ie. 1, 2, 10, 50). So, if you divide 50 by 2, you will get 25. That means that 50 is divisible by 2, because when you divide 50 by 2, you get an integer.

Understanding the rules of divisibility naturally requires you to understand remainder. You’ll absolutely get the remainder problems correct after watching this lesson. In this video I break down how you can quickly and easily find the rules of divisibility:

In case you want a quick cheat sheet, I actually put together a PDF magical cheat sheet. Cool, huh? Download Now

Fractions, Percents, and Percent Change on the SAT

The SAT assumes you have knowledge of fractions and fraction conversion. And this knowledge is required many times throughout each SAT math section. A random percent or decimal answer may require a fraction answer choice, or vice-versa. Switching between fractions and percents is pretty much required, mathematically, on the SAT, and in this video, I remind you how to do that.

Equally important (and pretty easy once you remember how to do it) is percent change. Imagine preparing that beach body for spring break. Everyone knows hot people like to be around hot people. So, once you start to prep for Spring Break, or summer, or whatever it is that you do that requires you to be fit for the boys (or girls) that you are trying to impress, you are going to have to either lose weight or put on weight (few people like skinny boys, most people like skinny girls… go figure).

If you are 120 pounds (54 kg) now and gain 20 pounds, you just increased your weight by 16%. But, if you go on a no-food bender after spring break and lose those 20 pounds all over again, you only lost 14% of your weight. WHAT THE HECK!?!? Watch the video now to figure out how that is even possible.

The Final Word

SAT Math is not hard. But it does ask a lot of you. It is your job, then, to answer right back. If you work through these videos and you have questions, ask those questions in the comments. If these videos are helpful, let me know. Deep down, the lesson I want to instill here is that you KNOW all that you are supposed to know for the SAT, but you may have either forgotten how to implement or forgotten how to use. Either way, together we will rock through your misunderstandings, clear up any issue, and really, thoroughly, and completely make the SAT a little inside joke.