As an SAT and ACT prep tutor with several years’ experience working one-on-one and in small groups with high school students, I’m often shocked to note how little students know about their calculators. Powerful graphing calculators such as the TI-84 and TI-89 are NOT cheap, yet most students only use them for simple operations like adding, subtracting, multiplying, and dividing. Very few students know just how powerful their calculators are. Students who take the time to master these calculator tips, tricks, and hacks will find themselves with quite a favorable advantage on test day over students who have no idea how to work their devices. I hope you enjoy this list of ideas for your calculator!
Tip #1 – Know Thy Calculator BEFORE Test Day
Practice with your calculator before taking the SAT and ACT. You should know how to use your device and learn about all its features before the day of the test. The last thing you want to do is waste precious time fiddling with a device you don’t know how to operate. Graphing calculators are powerful tools, and in order to take full advantage of what they offer, spend some time reading the user manual and reading blog articles containing information on calculator tips and tricks. Chances are your graphing calculator can do things you aren’t even aware of!
Tip #2 – the MATH button
Use the MATH button to convert fractions to decimals and vice versa. When you hit the MATH button on a TI graphing calculator, you’ll see a menu with options FRAC and DEC to convert answers to fractions and decimals respectively. If you need to cube something, or take the cubic root of something, or take another type of root of something, there are options for that as well. You can also use the calculator find the minimum and maximum values and coordinates of a function you’ve graphed.
Tip #3 – Use programs from TIcalc.org
Use programs to perform difficult operations, such as FOILing, factoring quadratics, solving quadratic equations using the quadratic formula, solving systems of equations with two variables, and much more. Learn more about how to obtain and install these programs at the TI calculator web site www.ticalc.org
When downloading programs, it’s important to be sure you’re choosing the correct version of the program for your calculator. Be sure to note which calculator each program works, and ensure that the operating system of your calculator is compatible with the program you’re attempting to obtain.
The Quadratic Formula
The quadratic formula is “Negative B plus or minus the square root of B squared minus 4ac all over 2a.” It’s used to reveal the x-intercepts of a quadratic equation, also called the “roots” or “zeros” of the function (because the x-intercepts occur when y = 0). It’s vitally important to memorize the quadratic formula, as some questions on the SAT’s No Calculator Math section require you to use this equation, but when seeking to find the x-intercepts of a quadratic on the Calculator Math section or on the ACT (which allows a calculator), a quadratic formula program on your calculator could be indispensable. Simply visit ticalc.org and search the site for “quadratic formula” and you’ll find plenty of programs you can install that will allow you to enter values for A, B, and C in your quadratic equation and quickly solve for the zeros of the function.
Many students detest factoring and find it too time-consuming and tricky to be worthwhile. Quadratic equations can be displayed in the form ax^2+bx+c, which reveals some information about the graph of the function at a glance (such as whether it opens upward or downward, whether there is horizontal shift and if so how much, and the y-intercept). Factor form is simply another way to represent an equation, and it tells you the zeros of the function at a glance.
It’s important to know how to factor without using a calculator for the SAT’s No-Calculator Math section, but for the ACT and the SAT’s Calculator Math section, why not let your calculator do the heavy lifting? Search ticalc.org for “factoring” and you’ll find a litany of programs that will prompt you to enter the a, b, and c values of the quadratic. It will do the factoring for you quickly and easily!
(To factor without a calculator, remember you’re looking for numbers that multiply to the c constant and add to the b constant)
Graphing Functions to Visualize Them
You don’t need any special program to take advantage of this feature, but you’d be surprised how few students truly feel at home using the graphing ability of their graphing calculator. With a graphing calculator, you can graph equations and systems of equations and find their minimum, maximum, point of intersection, intercepts, and so on. You can even use your graphing calculator to graph inequalities and systems of inequalities. Take some time to learn how to graph functions and how to gather data about the functions that you graph. Your time will be well-spent when you’re able to answer questions about functions much more quickly and more accurately than your peers.
Solving Systems of Equations with Two Unknowns
A very common topic on the SAT and ACT is solving systems of equations. Some systems have one solution, some have multiple solutions, some have no solution. To find out, you can use algebra (substitution, elimination) or you can let your calculator do the solving for you. At ticalc.org a quick search for “systems of equations” will yield many programs that simply prompt you to enter the constants in each equation and will do the algebra for you.
Getting the Equation of a Line
If you know two points, you can get the equation of the line they describe by calculating the slope of the line (Y-2 minus Y-1 over X-2 minus X-1) and then using the x and y coordinates of a point in the y = mx+b equation to solve for the y-intercept. You can also, however, get a program at ticalc.org that does it for you. Simply enter the two points that describe the line whose equation you’re seeking and let the calculator work its magic. Alternatively, you can get a program that allows you to enter a slope and one point and it will get you the equation of the line. Be sure the equation is in the form you need it in—the most useful form for a linear equation on the SAT and ACT is y=mx+b, as it allows you to graph and visualize lines with ease as well as perform substitutions to solve systems by setting two lines equal to one another and solving for x.
Take the Time to Learn What Your Calculator Can Do
There are many things not listed here that your calculator is capable of doing. Because math is a straightforward and rule-governed process, algorithms can simplify even the most difficult calculations. Knowing tips, tricks, and hacks for your graphing calculator and downloading useful programs for your TI calculator will give you an edge on the competition. Don’t be the person who only knows how to add and subtract on their calculator! Also, though, don’t be the person who has no idea how to do algebra and geometry problems without a calculator. It’s important to be versatile.
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That’s it! For more SAT and ACT math tips, tricks, and hacks, as well as a wealth of SAT and ACT prep tips, check out the rest of our blog. Looking for 1-on-1 ACT or SAT prep tutoring? Want to join an SAT or ACT group class? Contact us today!