# Math Help - Can you manually compute cube root like you do square root?

1. ## Can you manually compute cube root like you do square root?

Can you manually compute cube root like you do square root?

2. ## Re: Can you manually compute cube root like you do square root?

I'm not sure what you mean by manually computing a cube root. Actually to be honest, I'm not sure what you mean by manually computing a square root either...

What method do you use to compute square roots? I know of several, but none of which I would do manually...

3. ## Re: Can you manually compute cube root like you do square root?

Hi hisajesh,

To take a "cube root" of a number, we seek another number, that when multiplied by itself 3 total times, is equal to the original number.

(Quick notation: Taking the cube root of "x" is the same as saying, x^(1/3))

As an example, if we are looking for the cube root of 8, we have to think about a number multiplied by itself three times, that is equal to 8.
In this example, since 2*2*2 = 8, we say that 2 is the cube root of 8 (or also 8^(1/3) = 2).

Does this make a little more sense?

4. ## Re: Can you manually compute cube root like you do square root?

@Prove It: I meant without using calculator or other computing device or program.

5. ## Re: Can you manually compute cube root like you do square root?

Yes, but most algorithms will have that many calculations of decimal values (and some even include divisions - a complete nightmare) making it necessary to use a calculator at some point.

This is why I asked, what is the algorithm you use for manually calculating square roots. Just out of my own interest

6. ## Re: Can you manually compute cube root like you do square root?

See whether this is what you are looking for

Math Forum - Ask Dr. Math

I sort of remember being taught this technique back in the 50's, but it was inefficient even then: logs (and slide rules) were quicker and less prone to error. I can't imagine teaching it in an age of cheap, reliable calculators.

7. ## Re: Can you manually compute cube root like you do square root?

Hi

If you are interested in cube roots as a mathematical concept then using the Newton-Raphson method is an numerical iterative technique that can achieve it.

Regards