X Factory Test Prep

Calculators! I have a lot to say about this topic. So, let's jump right in and investigate the most updated SAT Calculator policy – as of August 2025 – and why I recommend bringing a TI-84 Plus graphing calculator to the exam.

First, an online graphing calculator is available to use during the SAT. It's called 'Desmos', and yes, it's great at a LOT of things. If you haven't used it before, its capabilities might surprise you. And even if you HAVE used it, chances are you haven't used it to its fullest capacity. All of Module 3 of my course Streamlined SAT Math is dedicated to learning how to use Desmos to do a variety of things much faster and more accurately than without it. In many cases, it even makes a question possible to do – much more math knowledge would be required to answer that question without it. Practice with the exact version of Desmos that's built in to the SAT: https://www.desmos.com/testing/cb-sat-ap/graphing.

Here's where it gets even better:

You are also allowed to bring a handheld calculator to the test, to use in addition to Desmos. The calculator you bring with you must be an approved type. Below is my summary of what is allowed and what is not allowed, with some clarification and commentary. (You can read the full policy without my commentary here, if you want: https://satsuite.collegeboard.org/sat/what-to-bring-do/calculator-policy)

CAS calculators are not allowed. 'CAS' stands for 'computer algebra system', and these calculators will have the 'CAS' designation in the model name. These are calculators that solve equations and manipulate algebraic expressions symbolically. For example, if you type in 'x+x', it will produce the output '2x'. And if you ask it to solve the equation 'x²-8=0', it will produce the solutions 'x=2√2, x=-2√2. Non-CAS calculators only output numbers as decimals or fractions, not with other math symbols.

Non-CAS graphing calculators are allowed. The TI-84 Plus is in this category. It can't solve equations symbolically, but it CAN solve them numerically. It can't simplify expressions symbolically, either – it will instead output a decimal or fraction. On the TI-84 Plus, if you type 'x+x', it will not answer '2x'. It will instead take the number you have stored as 'x' and add it to itself. The output will a number that is double the value that you've stored as 'x'. Solutions to equations will be numbers in the form of decimals or fractions, without the use of other math symbols, such as √ or π.

For calculators that hold programs, there is this requirement: "You must remove programs that have algebra functionality (e.g., solving equations, expanding algebraic expressions, factoring algebraic expressions, etc.) from your calculator." These would be programs that can do the things that the CAS calculator can do, so remove those. Keep in mind that numerical solving is allowed – it's a built-in function after all – so programs that do numerical solving do not need to be removed. Proctors are not instructed to require students to clear all stored programs. It is my recommendation that if you are asked to clear out the programs, or 'clear the RAM', you should present a printed copy of the calculator policy to show that this is not required. It's very unlikely this will happen, but you never know what personal agenda an individual proctor might have.

Students enrolled in my course Streamlined SAT Math receive many programs for the TI-84 Plus calculator. These programs don't have 'algebra functionality', meaning that they don't do the things described above, that the CAS calculators can do. Don't worry, though, you don't need a symbolic equation solver, because the built-in numeric equation solver is just as useful. Desmos solves equations numerically, too. And if you learn how, you can get either the TI-84 Plus or Desmos to identify equivalent expressions – numerically, of course!

If your calculator can store documents, you are required to remove them. You can't have textbooks or notes stored, for reference. Programs are not documents.

Just a note: Students have reported to me for years that the proctor only checks the model of the calculator to see that it is allowed – nothing else. While this is just anecdotal evidence, it suggests that you aren't going to get into it with a proctor over whether or not a particular program has a prohibited capability. There just isn't time for that, and proctors are probably not knowledgeable in the workings of every model of calculator that might be brought to the test. Still, play by the rules.

Scientific and four function calculators are allowed, too, but ... don't bother. They won't give you any advantage. The TI-84 Plus is the best option to achieve things that Desmos won't do.

I'm just going to say it: If you aren't using a TI-84 Plus graphing calculator, you are leaving points on the table. Plain and simple. It's the best calculator to supplement what Desmos does: it's user friendly, has loads of built-in capabilities, and it runs all of the programs available in my online course. I require students to have this calculator when they sign up for tutoring sessions with me.

All models of the TI-84 Plus are approved for use on the SAT. Which model should you get? I address that in the first FAQ question here: https://www.xfactorytestprep.com/links. If buying a new one isn't in your budget, check Ebay or similar for a used one. Happy testing!

As you might imagine, I see a lot of SAT-Math-related stuff on Pinterest (and everywhere else). I usually don't click into any of it, because I know it's just the usual, standard, boring, run-of-the-mill advice. It typically goes like this: "Study the heck out of everything and memorize a ton of stuff." But sometimes I want to remind myself that everyone else is still approaching this the hard way, while I'm doing it differently. So I peek.

Today I came across a pin entitled "18 Formulas You Need for the SAT". It has 2.5K likes and 320 comments as of the time I'm writing this.

It gave me an idea: Let's debunk it!

Here's my response to every item on the list of essential formulas to memorize:

1. Slope of a line

Not necessary. My TI-84 Plus program does this (plus, it finds distance and midpoint, too).

2. Slope-intercept form

The SAT is not going to ask for 'slope-intercept form' by name, but the answers might be in that form, or possibly another form. One of my TI-84 Plus programs will find the equation of a line in that form, and also 'standard form'.

3. Midpoint formula

As stated in #1, just use my program.

4. Distance Formula

This is getting tiring. Same program as for #1 and #3.

5. Length of an arc

I have a program for that, too. It will also find the area of the sector and segment. 3-in-1.

6. Area of a sector

Didn't I just address that in #5? Yup.

7. Quadratic formula

Another program takes care of this. A longer option is to use Desmos. The absolute longest, most time-consuming option is to actually use the quadratic formula on your own. Why waste time on that, and risk careless mistakes?

8. SOHCAHTOA

Achieve this, too, with one of my programs.

9. Probability

I'm actually working on this program right now, and it should be available soon. It will find simple probability, 'and/or' compound probabilities, permutations and combinations, and variations of them. You'll be able to use it for probability and 'how many ways are there to..." questions.

10. Equation of a circle

My response: Why, why, WHY would you bother memorizing this!? You can graph anything on Desmos and circles are no exception. Just graph it and see if it's the circle you want. Still want a reminder of the standard form? The TI-84 Plus has a built-in app for this, too.

11. Exponential growth

Desmos and/or the calculator can graph whatever you give it, and create tables of values. You won't need more than that to answer any question about exponential functions. The one thing you might have to know is what exponential growth (or decay) actually looks like on a graph, but that is waaaaay easier than memorizing a formula and what-goes-where in it.

12. Arithmetic sequence

One of my programs does it.

13. Geometric sequence

Same program as for #12.

14. Vertex of a parabola

Really? Just graph it on Desmos and LOOK at where the vertex is, instead of memorizing yet another formula you might mix up with another one when it matters.

15. Degrees to Radians

Use my program to achieve this.

16. Vertex form (of a parabola)

What I said for #14. You won't have to write the equation yourself. At most, you'll be asked to choose which equation produces a parabola with specific properties. GRAPH IT on Desmos!

17. Pythagorean Theorem

I have a program that finds the 3rd side of a right triangle. Plus, it finds missing sides of 45-45-90 triangles and 30-60-90 triangles. Also, if you really want to do this by hand (if you can get the answer in 10 seconds or less), the Pythagorean Theorem is on the formula sheet provided on the SAT.

18. Area of a triangle

My response: Yup, I have a program for this, too. Two of them actually. One program for the 'easy' triangle, where you have the base and height values. Another program for the triangles that aren't the 'easy' ones.

Alright. I hope you are convinced that the advice given on that pin I referenced at the beginning is just perpetuating the myth that you have to relearn everything. You don't, you really don't!

Now, I'm not saying to forget all this stuff if you know it already. But for the SAT: if you don't know the formulas – and even if you do – use the programs and Desmos anyway! Most of the time, it's faster and more accurate. The technology doesn't make careless mistakes!

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Top 5 Tips for SAT Math Success

1. Make Friends With Desmos
The SAT has the Desmos graphing calculator built in. Learn what it does and practice with it. Many difficult-sounding problems become absolutely obvious when you just graph the equation, for example. Without Desmos, those questions would require a much deeper understanding of the math, and probably knowing some formulas, too. Even if you DO know the "real" math, you'll be faster and more accurate by using Desmos. Our online course X Factory Test Prep: Streamlined SAT Math has an entire Module devoted to the many ways you can outsource the math to Desmos.

2. Use Your Calculator as a Tool, Not a Crutch
Most students underuse their calculator. Beyond basic arithmetic, it can:
• Test answer choices quickly
• Graph functions and find important parts of graphs (much like Desmos!)
• Handle repetitive or messy "order of operations" calculations efficiently, without mistakes
• Apply algebraic and geometric formulas and theorems in seconds
• Find solutions to ANY equation
When used strategically, the calculator eliminates entire methods and entire opportunities for mistakes. It even eliminates the need to know formulas and some theorems. So YES, you absolutely should bring your TI-84 Plus calculator to the test – it's my pick for the best functionality. It does a lot of things that Desmos doesn't. We're going to talk a LOT about this, so stay tuned. For a head start, learn more here.

3. Learn To Feel OK with Not Knowing the Math
This one sounds strange, but it's true! Some SAT Math questions are designed so that doing the full math is actually the slowest option. Plugging in values, working backward from answers, or checking choices directly can often get you to the right answer faster — even if you don’t remember the "real" math. Not knowing the “traditional” method doesn’t mean you’re stuck! "I don't know" just means to shift gears and use one of your backup strategies.

4. Speed Comes From Decisions, Not Practice Alone
If you know how you’re going to approach a problem the moment you see it, you're naturally going to be faster. If you’re deciding what to do mid-problem, you’ll waste time – and time is limited. The fastest test-takers aren’t faster at math. They’re faster at choosing the right strategy. Learn which types of questions send you straight to the calculator, or to Desmos, or to a different strategy. Learn which types are best to solve the "real" way, if you know it.

5. Don't Take The Bait
The test makers figure out the answers produced when people make common mistakes, and they put those answers in the choices to trap you. Don't fall for it. In some cases, you can judge the questions by its placement in the module. Early questions tend to have simpler solutions. If you find yourself using a very simple method — something you would have known in 3rd grade — on a question that's late in the module, you probably missed something. Keep the psychology of the test in mind, to catch those mistakes and fix them.

The Big Takeaway
Notice that not one of these tips said "Break out the textbooks and relearn the last 3 years of math." SAT Math isn’t about relearning everything. It’s about using the right tools, recognizing patterns, and choosing efficient strategies.
If you’re short on time or want a smarter approach, learning how to think about the test can make all the difference.

I can't scream this loudly enough: Don’t treat the SAT like a test for your school math class!

The SAT doesn’t reward 'real math' the way school does — you don't have to do the problems the way you learned in school. In fact, many times it is just a waste of time to do that! While it's great if you know those methods, they may be slowing you down. During the SAT, nobody is there to approve or disapprove of your methods and nobody will look at your work afterward. The SAT rewards choosing the most efficient path to the correct answer, period.

👉 The goal isn’t elegance. It’s efficiency.

This is why much of the time you don't even have to know the 'real way' to get the right answer. (Sometimes you do, but that's only for a few of the hardest questions.)

But what if you're SO used to doing things that way – the way your teachers have trained you? What if, when you see a complicated equation, you jump right into solving it by hand? Best case scenario: it takes more time than you should have spent, but you get the right answer. Good, right?

Ehhhh, maybe not. Maybe you get the right answer, but you waste precious time. Worse, maybe you make a common Algebra mistake, and choose a wrong answer choice that the test makers put there to trap you.

You don't fall for the traps? While that's possible for some people, it's unusual. And surely you make careless mistakes, especially under pressure, while rushing to get to the end of the section before the time runs out. Right? You've been trained by your teachers to show all your steps, BUT doing more steps means more opportunities to make a careless mistake.

So what do we do about this?

Let's first agree that the best approach is to get to the correct answer by whichever path is fastest, regardless of whether your teacher would approve. Okay? Good.

Achieving that will take a change in your approach. It takes practice to resist diving in the way you're used to. It takes practice to resist the temptation to guess at a procedure in the middle of the test... because you think you kind of remember three years ago your teacher said something like that thing you're thinking of. It takes practice to know when to shift gears.

I've told you what not to do, but what is there to actually do? That's where all the tools and strategies come in. Your two best tools are your calculator (the TI-84 Plus, of course), and Desmos.

Desmos is built in to the test, so make friends with it, practice with it, and use it whenever you can. Some things such as solving equations and finding features of graphs can be completely outsourced to Desmos. As in, you don't have to know it yourself. At. All. If you do know how to do it yourself and you're fast, fine, but double-check it with Desmos. You can even do all the 'finding equivalent expressions' problems on Desmos.

The TI-84 Plus is the perfect calculator to bring with you to the test. Yes, it's allowed, and it can be used to outsource and automate all sorts of other types of problems. These methods are the main focus of my course Streamlined SAT Math. It's more accurate than you are. Heck, it's more accurate than I am, and I've been an expert at this for decades.

Other strategies exist too. You've probably heard people say to test the answer choices. That's an age-old strategy, and good one. But there are also some you haven't heard of before - methods for getting the answers to word problems without knowing the formulas. Methods for deciding which complicated-looking formula models a scenario without knowing anything about 'what number goes where' in the formula.

All of these methods, taken together, help you
(1) do questions faster and more accurately, so you don't feel rushed or make careless mistakes.
(2) get the right answers to questions even when you didn't know the math yourself.

They amount to a very strong army against SAT Math questions and a comprehensive insurance against not knowing the math.

So, here's a variation of what I've been saying: When you see a problem and don't know the 'real way' to solve it, that's OK. Let other people decide they can't do the problem. They'll skip it, invent a method, or just randomly guess. But not you! You know you don't NEED to know the 'real way' because you have alternate paths to the correct answer and they are probably faster anyway!

And that means that no, you don't need to relearn all that math you forgot or haven't learned yet. What a relief, right?

Start with what you do know, add the best tools available, and it's going to be great!