My Math Forum  

Go Back   My Math Forum > College Math Forum > Number Theory

Number Theory Number Theory Math Forum


Reply
 
LinkBack Thread Tools Display Modes
August 22nd, 2013, 09:37 AM   #1
Math Team
 
MATHEMATICIAN's Avatar
 
Joined: Jul 2013
From: काठमाडौं, नेपाल

Posts: 842
Thanks: 60

Math Focus: सामान्य गणित
how to find number of factors of a number ?

also how to find the sum of the factors ?
MATHEMATICIAN is offline  
 
August 22nd, 2013, 11:04 AM   #2
Senior Member
 
Joined: Mar 2012
From: Belgium

Posts: 653
Thanks: 11

Re: how to find number of factors of a number ?

There is not an obvious solution for this. What you should do is factorize your number and count them or add them.
gelatine1 is offline  
August 22nd, 2013, 11:20 AM   #3
Math Team
 
MATHEMATICIAN's Avatar
 
Joined: Jul 2013
From: काठमाडौं, नेपाल

Posts: 842
Thanks: 60

Math Focus: सामान्य गणित
Re: how to find number of factors of a number ?

Quote:
Originally Posted by gelatine1
There is not an obvious solution for this. What you should do is factorize your number and count them or add them.
i think thats an absurd idea.
MATHEMATICIAN is offline  
August 22nd, 2013, 11:52 AM   #4
Senior Member
 
Joined: Mar 2012
From: Belgium

Posts: 653
Thanks: 11

Re: how to find number of factors of a number ?

Imagine a prime number. according to you it must be easier then factorizing your number to determine the amount of it's prime factors. Well then it should be easy to determine that it's amount of prime factors is 1 and is a prime. I hope that you know that it is not that easy to determine if a number is prime or not.

Or something else. Imagine 21 and 23. Is there anything about these numbers that tell you that one of them has 2 prime factors and the other only one ? No.
gelatine1 is offline  
August 22nd, 2013, 12:03 PM   #5
Math Team
 
MATHEMATICIAN's Avatar
 
Joined: Jul 2013
From: काठमाडौं, नेपाल

Posts: 842
Thanks: 60

Math Focus: सामान्य गणित
Re: how to find number of factors of a number ?

suppose i've a number 900,
i would take me very long time to search each and every factor of this num.
isn't there any quick way, may be some formulas ??
MATHEMATICIAN is offline  
August 22nd, 2013, 12:33 PM   #6
Newbie
 
Joined: Nov 2011

Posts: 26
Thanks: 0

Re: how to find number of factors of a number ?

If a formula is all you need there is one.. Let the number concerned be ,
if it prime factorisation is then it has factors
i.e you multiply the powers of its prime factors after adding one as per formula..

Hope you understand me
MathMonster is offline  
August 22nd, 2013, 12:53 PM   #7
Math Team
 
MATHEMATICIAN's Avatar
 
Joined: Jul 2013
From: काठमाडौं, नेपाल

Posts: 842
Thanks: 60

Math Focus: सामान्य गणित
Re: how to find number of factors of a number ?

mr. monster
i hope i'll understand that by the end of the century
MATHEMATICIAN is offline  
August 22nd, 2013, 01:09 PM   #8
Newbie
 
Joined: Nov 2011

Posts: 26
Thanks: 0

Re: how to find number of factors of a number ?

For example lets taake N to be 18;


we take the product of the expoents of the factors plus one
The exponent of is and the exponent of is
Hence the number of divisors is

Hope now u understand
MathMonster is offline  
August 22nd, 2013, 01:14 PM   #9
Senior Member
 
Joined: Mar 2012
From: Belgium

Posts: 653
Thanks: 11

Re: how to find number of factors of a number ?

Quote:
Originally Posted by MathMonster
For example lets taake N to be 18;


we take the product of the expoents of the factors plus one
The exponent of is and the exponent of is
Hence the number of divisors is

Hope now u understand
Oh I thought this problem was only about finding it's prime factors. and not about all factors. but anyway We still need to factorize our number.
And by the way finding the prime factors of 900 is not really a hard thing to do...
gelatine1 is offline  
August 22nd, 2013, 01:17 PM   #10
Math Team
 
MATHEMATICIAN's Avatar
 
Joined: Jul 2013
From: काठमाडौं, नेपाल

Posts: 842
Thanks: 60

Math Focus: सामान्य गणित
Re: how to find number of factors of a number ?

i think i get it now,

if i've,
num = 2^3 * 5^4 * 3^3

num of fac = (3+1)(4+1)(3+1)
is it so ?
MATHEMATICIAN is offline  
Reply

  My Math Forum > College Math Forum > Number Theory

Tags
factors, find, number



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Number of factors of summation eddybob123 Math Events 1 February 8th, 2014 12:04 PM
Combinations : regarding factors of number rnck Advanced Statistics 4 June 21st, 2013 04:26 PM
property of numbers of factors of factors of a number mathbalarka Number Theory 15 June 15th, 2012 07:36 PM
Finding the factors of a number. jdraughn Elementary Math 4 November 25th, 2009 09:59 AM
prime factors of a number sangfroid Number Theory 4 November 3rd, 2007 02:12 PM





Copyright © 2017 My Math Forum. All rights reserved.