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Reciprocals, Exponents and Radicals

Reference > Mathematics > TI-30X II

Your calculator knows how to handle both exponents and radicals, so let's take a quick look at how to do both of these!

There is a special key just for squaring a number. It looks like this: x2. If you wanted to square the number 7, you would press 7, followed by the SQUARE button. Press ENTER to see the result.

Other Powers
But what if you want to raise seven to the third power, instead of squaring it? Well, this is almost as easy. Find the caret button (a caret looks like this:</strong>). Now press: 7 3 = and you will see the result: 343.

A reciprocal is a special power; it's a number raised to the -1 power. It's also what you get by swapping the numerator and denominator. There is a special key for reciprocals. It's the x-1 key.

So let's find the reciprocal of 5. We press 5 x-1 = , and we get an answer of 0.2.

Square Roots
There is also a special key for taking a square root. It's the 2nd function of the SQUARE button. If you want to take the square root of 81, press 2nd SQUARE 81 =, and the calculator will show you the result: 9.

I hope you noticed that there is an open parenthesis between the square root sign and the number 81. This means that until you put a close parenthesis, everything is considered to be part of the square root. If you never hit a close parenthesis, when you hit enter, the calculator assumes that you meant to put the parenthesis at the end of what you typed.

Why is this important? Consider the following:

+ 3
(81 + 3

Notice that in one of those I put a close parenthesis and in the other I didn't. Try entering both of those into your calculator. Do they give the same result?

Parentheses are important!

Other Roots
Can you take a cube root? Absolutely! Or a fourth root. Or a fifth root. You can even take 1/3 roots if you really wanted to!

Find the caret key, and notice that an x-root symbol is directly above it. You know what that means! It's the 2nd function.

So suppose you wanted the cube root of 64. Here is what you would type:

3 2nd 64 =

The result is 4.


What is two to the 16th power?
What is the square root of 256?
What is the square of the sum of five and four?
What is the square root of the sum of 127 and 42?
What do you get if you add 7 to the square root of 441?
What is the cube root of 1331?
What is the square root of 121, plus the square root of 100?
What is the reciprocal of 16?
What is the result if you take the square root of 10 - 15?
What is the response if you try to take the reciprocal of zero?
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