# SAT – Common Math Misconceptions

## ‘1’ is a prime number

‘1’ is not a prime number because a prime number is divisible by only itself and ‘1’. Since ‘1’ is itself, it doesn’t really fit the definition.

## ‘2’ is not a prime number

‘2’ is a prime number. Many think that because it is even it is not. But remember: a prime is divisible by only itself and ‘1’. ‘2’ is divisible only by itself and ‘1’. So it’s a prime.

## You must always use algebra to solve a problem

When you see a bunch of variables in the answer choices, do not be intimidated! You do not have to solve equations algebraically to get the right answer. Work backwards and plug in your own numbers to the variables. The answer choice that matches up with the information in the question is correct.

## Negative numbers are not integers

A negative can be an integer as long as it is a counting number. What’s a counting number? Well, I call counting numbers “people numbers.” Say you have ten people in a room and three leave. You now have -3 people. Therefore -3 is an integer. ½ is not an integer, because you can’t add half a person to the room.

## Author

• Chris Lele is the Principal Curriculum Manager (and vocabulary wizard) at Magoosh. Chris graduated from UCLA with a BA in Psychology and has 20 years of experience in the test prep industry. He's been quoted as a subject expert in many publications, including US News, GMAC, and Business Because. In his time at Magoosh, Chris has taught countless students how to tackle the GRE, GMAT, SAT, ACT, MCAT (CARS), and LSAT exams with confidence. Some of his students have even gone on to get near-perfect scores. You can find Chris on YouTube, LinkedIn, Twitter and Facebook!