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# what is factoral?

how to do a bigger number

### 2 Answers by Expert Tutors

Steve S. | Tutoring in Precalculus, Trig, and Differential CalculusTutoring in Precalculus, Trig, and Diffe...
5.0 5.0 (3 lesson ratings) (3)
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"what is factoral?" [You missed the "i" in factorial.]

If n is a non-negative integer, then we can find its "factorial".

n factorial is written in math as "n!". I.e., we use the exclamation point to denote factorial.

3! = 3*2*1, where * means multiplication.
10! = 10*9*8*7*6*5*4*3*2*1
n! = n*(n-1)*(n-2)*...*2*1

AND 0! := 1, where “:=“ means “is defined as”.

On my calculator I have a key labelled "x!".

If I key in 20 and press x! I get 2.43290200817664*10^18.

But if I key in 200 and press x! I get "Overflow" on my MacBook or "Error" on my iPhone.

What's the largest integer you can key in on your calculator and press "x!" without getting an error? [An error means you've exceeded the capacity of your calculator. In computerese you have an overflow error.]

You can also key in a non-negative real number and "x!" will give you a result. How does it do that? It uses a function of real numbers that equal n! for non-negative integers but that essentially draws a smooth curve between the graphed points of y = n!. See http://www.wyzant.com/resources/files/265570/x_factorial AND http://en.wikipedia.org/wiki/Factorial#Extension_of_factorial_to_non-integer_values_of_argument.

E.g.: (pi)! ≈ 7.188082728976031
Kay G. | ~20 Years Accounting Tutoring Experience~20 Years Accounting Tutoring Experience
4.9 4.9 (32 lesson ratings) (32)
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A factorial is written as x!

It means start with x and keep multiplying by the next lower number, all the way to 1.

For example:

5! = 5 * 4 * 3 * 2 * 1

A scientific (or financial) calculator should have factorial on it, x!

What do you mean by doing a bigger number?  What exactly are you trying to do?