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Thomas Broderick

ACT Math Tricks: Backsolving

Welcome back to Mr. B’s virtual ACT Prep class! I hope you’re all bright eyed and bushy tailed. If not, take a lesson from this little guy:


act tricks -Magoosh


So today we’re going to be talking Math, and a BIG TRICK you can use to make your time on the ACT Math a little less stressful.

Today’s Lesson: Backsolving

You may know backsolving by another name: Plug n’ Pray. But if you know what you’re doing, there’s no prayer necessary while performing this simple ACT trick. Let’s get started with this short, simple, yet valuable lesson.

What is backsolving?

In the smallest of nutshells, backsolving is plugging in possible answer choices into an equation to find the correct answer.

Now you may be thinking, ‘I already knew how to do that! Why’s there a whole article about it?’

Well, there is a certain amount of skill to backsolving. It’s a little like chess. You can learn how to play it in five minutes, but it can take a really long time to do well.


act tricks -Magoosh

Backsolving on the ACT Math is actually a lot easier than chess.


How do I backsolve well?

Here’s where the trick comes in. On the ACT Math Test you will have five possible answer choices. Even if they’re not listed from smallest to largest, find the number that falls in-between the other options. Plug that number in. If that’s the answer, great. Next question! But if not, you’ve automatically eliminated another 2/5 possible answer choices. Here’s a simple example:

6x = 60  What is the value of x?

  • 4
  • 6
  • 8
  • 10
  • 12

If we plug in 8, we get 48, which is lower than sixty. That means answer choices A and B are also incorrect, as they also result in answers less than sixty. From that point we only have to backsolve D and E to realize that the correct answer is D, 10.

Though the problems you will encounter on the ACT Math Test will be significantly more difficult than ‘6x=10 What is the value of X?,’ The same trick applies in all questions where you can backsolve.

When can I backsolve on the ACT?

Good question. As my simple example included an ‘x’ value, the short answer is  some Algebra questions on the ACT Math Test. Pre-Algebra and Elementary Algebra may make up to 45% of the test questions. Backsolving works on any question where there is only a single variable.

When can’t I backsolve?

If there is more than one variable in the question (like algebraic equations with X and Y), I wouldn’t recommend it. It’s not impossible, but you should rely on other skill sets to solve more complex algebraic equations.

Now that you know the right way to backsolve, apply it to some ACT practice tests. You’ll quickly discover when backsolving is and isn’t the best way to solve a problem. With practice it should become second nature.

Happy studying, ACT scholars! I’ll see you next time.


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About Thomas Broderick

Thomas spent four years teaching high school English, social studies, and ACT preparation in Middle Tennessee. Now living in Northern California, he is excited to share his knowledge and experience with Magoosh's readers. In his spare time Thomas enjoys writing short fiction and hiking in the Sonoma foothills.

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