Buying and Using Calculators and Computers in Math

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Please save Texas Instruments Proofs of Purchase for Mrs. Shearer. These can help us get more equipment for our math classes.

Using the TI-84 for statistics problems

Which calculator do I really need?

If you are taking a math class you might want to purchase a calculator. Calculators are allowed on New Mexico State Competancy Tests beginning in the eight grade. There are many types available at prices ranging from $1.00 to well over $100.00. Here is what I recommend:

If you will not take advanced math or science, a simple calculator is plenty. It should have the basic four-functions of add +, subtract -, multiply x, and divide . In addition, most of these inexpensive calculuators now have the square root function, which can come in handy in Algebra and Geometry but is not absolutely necessary. These are available at dollar stores for $1 and at other places for about $5.

If you have trouble with fractions, there are basic calculators available that do fractions automatically. These cost between $5 and $15. I recommend the TI-15 calculators - these do a great job with fractions, including improper fractions and reduced form.

If you will take Trigonometry, PreCalculus, Calculus, Chemistry, or Physics, I recommend as a minimum a calculator that has parentheses ( ) and the trig functions: sine (sin), cosine (cos), and tangent (tan). These will cost between $20 and $30 for a good model. There are solar models available so you never have to buy batteries.

If you plan to major in math, science, or engineering in college you might consider purchasing a graphing calculator. These are improving at a phenomenal rate and the price is dropping, but they still cost over $100. For my students, I recommend you use the TI-84 graphing calculators or the TI-Nspire handheld that I have available in class until you are ready to go to college.

For college you will want either a TI-84, a TI-Nspire CX, or a comparable version from another manufacturer. My students who started with the TI-Nspire find it very easy, but if you learned on a TI-84, it is a little hard to make the transition. The TI-84 operating system can be upgraded for free to display in fraction mode.

For more information and product comparisons, visit the Texas Instruments, Hewlett-Packard, Casio, and Sharp web sites.

Once you have purchased your new calculator, be sure to visit the manufacturer's website for training and to keep your operating system up to date. For eaxample, older TI-84 caculators did not do fractions using a fraction bar, but if you update your caculator you get the fraction bar and entries that look like they should.

My Parents Say Calculuators are a Crutch

I have heard a lot of my students say their parents don't want them to use calculators because they think it is a crutch. In a way, they are right - but if you have a broken leg, a crutch is necessary.

So many of my students are really pretty darn bad at basic arithmetic. In a perfect world you would all be great at arithmetic, but the reality is that for a variety of reasons there are a lot of students who just can't do basic calculuations. Luckily for us, we have calculators available at reasonable prices.

Return to top buttonGraphing calculators are wonderful for "seeing" what an equation looks like. It can be used for graphical analysis by looking at the graph of the equation. Enter the equation using the Y= button on your calculator. You can see the graph by using the GRAPH button and adjusting the zoom or window. If you use the second function TABLE (same button as GRAPH) button, you can see the table of values and look at the equation in a numerical way. So the graphing calculator helps you to understand equations better.

Most of the standardized tests my students take - like NMCRT, SBA, and ACT - allow the use of a calculator. In fact, the Advanced Placement (AP) Calculus, Statistics, Chemistry, and Physics tests are impossible without a good graphing calculator.

Using a calculator wisely

Once you have a calculator you need to learn to use it correctly.

Here is an example of how to use your calculator to find the hypotenuse of a right triangle with legs that are 5 inches and 7 inches long. The things shown in tiger orange are special buttons to push on the calculator.

Set-up let c = length of the hypotenuse and a and b equal the lengths of the two legs
Formula Pythagorean Theorem a2 + b2 = c2
Substitute 52 + 72 = c2
Solve for c2 on the calculator, type in:
(5 x2) + (7 x2) Enter

the answer on the calculator should be 74

Solve for c take the square root of 74

the calculator will say 8.60232526...
this is reasonable, since it is easy to imagine a triangle with sides of 5, 7 and about 8 inches.

Round your answer since we started with only whole numbers, we want the answer to have 1 decimal place

the answer rounded is 8.6

Write the units the problem gave the lengths in inches, so your final answer is
8.6 inches

Graphing Calculators

Graphing calculators can be used in almost every class, but they are so powerful they can actually get in the way for beginning students. I don't recommend using a graphing calculator until you are at least at the Algebra I level and don't feel it is absolutely necessary until you are in PreCalculus or Calculus.

I have classroom sets of graphing calculators available for my students to use in class, so no one has to buy their own. If you do buy your own graphing calculator, be sure to actually read the user's manual! I know it is pretty boring, but it is the best way to learn how to use a complicated graphing calculator. Also be sure to go to the manufacturer's web site for help. My personal favorite is, which has model specific information for students, teachers, and parents.

If you are taking AP Calculus, daily use of the graphing calculators is reguired. The AP Calculus exam has half of the test with calculators and half without.


Computers come in very handy for lots of things relating to mathematics. Prices keep dropping and you can purchase a reasonably good desk top computer with some basic software for less than $300. In fact, there are even laptop and now netbook computers available for less than $400. I gave my husband an IPad for Christmas, and it is a pretty neat option if you have the money. Here are my tips when buying a computer for college:

Once you have your computer, check my resources page or run a Goggle search for math topics. There are a lot of programs out there that can help you in your math class.

If you want to do some minimal programming, you can use your spreadsheet program to set up formulas for solving quadratic equations, doing trig functions, and other basic computational things. Most of the word processing programs have graphics that can be used to illustrate math papers. I use an "Equation Generator" add-in for MS Word when I write your handouts and tests.

Comments, questions, or you just need some help? Send an e-mail to Mrs. ShearerE-Mail
Last Updated: 08/268/2012
K. A. Shearer 2007-2012
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