How will I find out factorial from prime number? (C programming)

Question

1.00/5 (1 vote)

See more:

Problem :
Now you have to solve an interesting problem. Any integer n (where 1 < n < 100, means values of n from 2 can be up to 99) to find the number of times a prime number exists by expressing the factorial of have to do Like, we know, 5! = 120 = 2 * 2 * 2 * 3 * 5. Here 2 is 3 times, 3 is 1 time and 5 is 1 time. So if the input is 5 the output will be: 5! = (2, 3), (3, 1), (5, 1). Do you understand one thing that at the beginning of n ?Is it going to be a hassle to figure out the value of the factorial and then break the original product? Because the value of n is maximum 99 and integers cannot hold the factorial value of any number greater than 12. "Actually this program doesn't need to figure out the value of n!. Just do a little math. And put the prime numbers from 2 to 99 into an array."

I can't understand how will I find out factorial from prime number? Please give me some clue .

What I have tried:

Here, the author said,  "Actually this program doesn't need to figure out the value of n!. Just do a little math. And put the prime numbers from 2 to 99 into an array."  
My question is how will I find out the factorial from this array (prime number)
Suppose, I copy the prime numbers into an array
then ?

Posted 20-Jul-22 12:27pm

Lara Thomas

Updated 21-Jul-22 6:20am

Add a Solution

Comments

Rick York 21-Jul-22 1:43am

Either put the prime numbers into an array or determine if a number is prime on the fly. With a decent algorithm, performance should not be an issue.

4 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Greg Utas · Answer 1 · 2022-07-20T13:41:00

This question is very poorly worded, but I think I get what it's looking for.

It wants to factor a factorial into a product of prime numbers, where each prime number also has an exponent.

n! = 1 x 2 x 3 x 4 x 5 x 6 ... x (n - 1) x n.

If you have an array that contains the prime numbers from 2 to 99, now do you see how you can use it? What can you do as you encounter the numbers in the above expression? 1? 2? 3? 4? 5? 6? Which of these are prime, and which aren't?

Patrice T · Answer 2 · 2022-07-20T18:37:00

Quote:
I can't understand how will I find out factorial from prime number?

May be it is because you don't.
The goal is not to find the factorial, but the product of primes that make the factorial.

Quote:
Please give me some clue .

The goal is to compute the product of primes from a factorial, but you know that a factorial is a product of integers. Do you really need to know the value of the factorial to get the answer. Something should ring in your head.

The job of programmer is about being smart, and this we can't teach you.

CPallini · Answer 3 · 2022-07-20T20:25:00

Quote:
My question is how will I find out the factorial from this array (prime number)
Suppose, I copy the prime numbers into an array
then ?

This is not the right question. Actually computing the factorial is not requested (on the contrary, the requirements suggest avoiding it).

Now, how could you possibly produce the requested output without actually computing the factorial?
Consider, for instance, 5.

You know

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

That is

5! = 5 * (2*2) * 3 *  2 * 1

Producing the output

(2,3), (3,1), (5,1)

Note that, if you procede from 2 to 99, having computed the output for 5, makes you know a big deal of the output for 6, because

6! = 6 * 5! = (2*3) * 5!

merano99 · Answer 4 · 2022-07-21T06:20:00

Solution 4

Exactly the same question was asked here as well.
math - How will I find out factorial from prime number? (c programming) - Stack Overflow[^]

Posted 21-Jul-22 6:20am

merano99

Comments

Patrice T 21-Jul-22 12:26pm

Is it worth a solution ?

How will I find out factorial from prime number? (C programming)

4 solutions

Solution 1

Solution 2

Solution 3

Solution 4

Add your solution here

Preview 0