Debunking the Formulas "They" Say You Need to Memorize for the SAT

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 this 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. My TI-84 Plus program LINES 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 #2 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. (It's really important for your school math classes. For that purpose, I'd say to fully understand the logic of each formula, so you never forget them again.) 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 makes careless mistakes.

See it for yourself! Inside the free Preview for my course, watch the lesson video called 'See a preview of the calculator programs in action'.