**Buy Your TI Calculators from mid-July to mid-August**

You’ll want to buy your TI 84 or TI 36 now if you’re in the market. This is the time, right before the school year begins, to buy from local retailers. Best Buy, Wal-Mart, and Target have their lowest prices on TI-84 and TI-36 calculators right now.

Unsurprisingly, they’ll raise those prices during the school year. For now, the best deal from a local retailer on a TI-84+ is from Target: $99.99 for the TI-84+ CE and $88.99 for the TI-84+.

**Buy Your TI Calculators Now, But Avoid the TI-83+**

Please do not buy the TI-83+ in order to save money. First, the model doesn’t have the apps that are embedded in the TI-84+. Second, the connector is an antiquated cable rather than a mini-usb. This makes data transfer difficult between calculators. While you might find folks with programs from another TI-83+, you might not have the correct connecting cable.

Instead, opt for the TI-84+. If you want to save money, opt for the TI-84+ rather than the TI-84+ CE. It has the mini-usb connection, so it’ll still be easy for data transfer. If you prefer battery-powered v. rechargeable, the TI-84+ is a good choice.

I tend to prefer the TI-84+ CE for a few reasons. First, you can charge it via the mini-usb to usb charger. Also, it is fast with data transfer (Standard A to Mini-B USB Connectivity Cable) and has sufficient memory to retain a lot of programs. Next, it is thinner and lighter than its TI-84+ counterpart. Lastly, it comes with embedded APPS that help with chemistry and algebra 2. Specifically, those are the Periodic Table and Sci Tools.

During the school year, the TI-84+ CE costs anywhere from $125-$165 new (higher as the school year progresses). However, now you can find them as low as $99. So, act soon.

**All TI-84 Models are SAT-legal (and ACT-legal)**

The TI-84 is legal for the SAT, ACT, SAT MATH subject tests (1 &2), and the AP Calculus Tests, both AB and BC.

Surprisingly, the TI 36x Pro, though not explicitly prohibited from use on the ACT, was taken away from a student of mine in the 2017/2018 academic year as an illegal calculator. This might have been a misunderstanding. Or, it could be due to some of the CAS functionality of the TI-36x pro, such as solving polynomial equations (up to the third degree) quickly (faster than the TI-84 without a program; even with a program, the TI-36x Pro can do it with fewer keystrokes), and solving systems of equations with far fewer keystrokes than the TI-84+.

You might be able to bring both the TI-36xPro and your TI-84 to the ACT. This way, you’d still be able to use your TI-84 during the test.

**TI-36X Pro**

The TI-36X Pro is less than $19 right now at WalMart. I’m not advocating buying it there specifically. It’s just that I prefer to buy anything electronic from a local retailer so that if there’s a defect within the warranty period, I can return it hassle-free. During the school year, you’ll see the same calculator retail for as high as $27 from your local Staples.

So, if you like either of these calculators, buy them by mid-August.

Oh, and you’ll prefer to buy calculators new just so that there are no problems with them. As a math guy, I can guarantee you that I’ve bought at least 2 dozen calculators in the last 20 years. I’ve not had a single problem with a store-bought calculator.

**Programs for the TI-84**

The TI 84 has the capacity for programs. There are about a dozen you can download from this site for use on the SAT or in your math class:

QUADFORM: quadratic formula: you input A,B, and C values of a quadratic equation; first two numbers are your answers; other DISC part is discriminant

LINEQ: gives you the linear equation in slope-intercept form, given two points; you input (X1,Y1) and (X2,Y2)

D2P: Distance between 2 points, given their coordinates; again, you input the coordinates of the two points as in LINEQ

RAD: simplifies radical expressions; you would enter rad50 as 50; answer would be 5rad2

PRIMES: provides you with a list of all prime numbers between 1 & 100

FACTORX2: factors quadratic expressions, such as x^2+5x+6; you input A, B, and C of quadratic expression

ARCLENGT: gives you the length of an arc of a circle; answer will be in x pi units

SECTAREA: gives you the area of a sector of a circle; answer will be in x pi units

MIDPOINT: gives you the midpoint of a circle, given the two endpoints in coordinate form

GEOMEAN: gives you the geometric mean of 2 numbers

HERON: gives you the area of a triangle given the side lengths; this is not limited to right triangles: this could be any possible triangle

LAWCOS: solves a triangle using law of cosines given two sides and the included angle

LAWCOSSS: solves a triangle using law of cosines given all side lengths (SSS); it will output the sides of the triangle in increasing side lengths

PYTRIPLE: gives you common Pythagorean triple side lengths of right triangles; saves a lot of time using this program than using Pythagorean theorem

SUMINT: gives you the sum of interior angles, sum of exterior angles, measure of each interior angle (assuming your n-gon is a regular polygon), and number of diagonals of an n-gon given the number of sides (n)

VERTFORM: You enter a quadratic function in the form of Y=Ax^2+Bx+C, inputting the values of A, B, and C. The program will then give you the vertex form of a parabola: Y= A(x-h)^2+k. The (h,k) is the coordinate of the vertex.

If you’d like to download these programs onto your TI-84+ (regular or CE), set up a session: