What is Divisibility: Definition and 170 Discussions

In mathematics, a divisor of an integer



n


{\displaystyle n}
, also called a factor of



n


{\displaystyle n}
, is an integer



m


{\displaystyle m}
that may be multiplied by some integer to produce



n


{\displaystyle n}
. In this case, one also says that



n


{\displaystyle n}
is a multiple of



m
.


{\displaystyle m.}
An integer



n


{\displaystyle n}
is divisible or evenly divisible by another integer



m


{\displaystyle m}
if



m


{\displaystyle m}
is a divisor of



n


{\displaystyle n}
; this implies dividing



n


{\displaystyle n}
by



m


{\displaystyle m}
leaves no remainder.

View More On Wikipedia.org
  1. W

    Divisibility problem cant use module just induction

    Hi all, Great forum, I have been reading some cool stuff here for about a month. Heres my question: Using induction prove that 5 divides 8^n - 3^n, n Natural Number. I know its true for n = 1, but I get stuck on the n = k+1. I don't know how to proceed from here: 8(8^k) - 3(3^k)...
  2. K

    Discovering Pairs of Positive Integers for Divisibility Puzzle

    Determine all possible pairs of positive integers (m, n) for which (n^3 + 27)/(mn - 9) is an integer.
  3. S

    Divisibility by 9: Solving x+y+z Problems

    This isn't a homework problem but I found it on the internet and can't figure out how to do it. It's one of those "divisible by whatever"-type problems which I never learned how to solve... I don't know how to work with this divisibility stuff when it's generalized to numbers like x+y+z. I...
  4. D

    Proving Prime Divisibility of 2^(2^n)+1

    Homework Statement Prove that if a prime p|2^{2^n}+1 then p=2^{n+1}k+1 for some k. Don't know how. I'm guessing by induction, perhaps?
  5. T

    Proving Divisibility of n by 6: A Simple Guide

    I need to prove that if n is a natural number and n^2 is divisible by 6, then n is divisible by 6. I know that I knew how to do this at one point fairly recently, if you could refresh my memory I would greatly appreciate it.
  6. A

    What Are the Possible Solutions for These Divisibility Questions?

    Hi, I am going through the book on number theory by ivan niven. well its tough book though, and i am stuck with problems in the first topic divisbility.Hope some help. 1. prove that a|bc if and only if a/(b,c)|c where (b,c) is the lcm of b and c. 2. Prove that there are no positive...
  7. M

    Can you see a counter example that i can't, divisibility problem

    HEllo everyone. I'm trying to find a counter example that will prove this false. But it may be true but I'm hoping it isn't :) For all integers a and b, if a|10b then a|10 or a|b. I said false, a = 3, b = 5. 3 is not divisible by 50. 3 is also not divisble by 10 nor 3 divisible by 5...
  8. O

    Prove/Disprove: c Divides (a+b) But Not a, Then c Does Not Divide b

    I'm having trouble with this question, I need to prove or disprove this statement: If c divides (a+b), but c does not divide a, then c does not divide b. what i have so far is ck = (a+b) where k is some integer. Next I have a=ck-b and b=ck-a. I tried doing things like a = ck-(ck-a) but...
  9. L

    Proving divisibility by induction

    Hello, I'm struggling with the question on induction. I was wondering if you could help me? Prove that n(n^2 +5) is divisible by 6 for n belonging to Z^+ P_1 is (1(1^2 + 5))/6=1 hence P_1 is true If P_k is true then (k(K^2 +5))/6=r and if and only if (k(k^2 +5))=6r then P_(k+1) is...
  10. D

    Mathematica Proof by mathematical Induction: Divisibility

    The question is: Prove by mathematical Induction that f(n) \equiv 2^{6n}+3^{2n-2} is divisible by 5. This is what I did: Suppose that the given statement is true for n=k Since the f(k) is divisible by 5, f(k)=5A (where A are is a constant.) Also, from the given statement...
  11. 1

    Proving Divisibility: Exploring Two Questions on Positive Integers

    Two questions here. I know the definitions, but cannot formulate a through proof. 1.a and b are positive integers. If a^3 | (is divisible by) b^2, then a | (is divisible by) b. Now, by definition, I know that a^3*k=b^2, for some k. Also, I know that a * j = b for some j. But where do...
  12. B

    Proving Divisibility by 3 for $\mathbb{Z}^{+}$ Sets

    Where \mathbb{Z}^{+} represents the set of all positive integers, How do I prove that \begin{gathered} \forall \left\{ {a_0 ,a_1 ,a_2 , \ldots ,a_n } \right\} \subset \mathbb{Z}^ + \;{\text{where}}\;\max \left\{ {a_0 ,a_1 ,a_2 , \ldots ,a_n } \right\} \leqslant 9, \hfill \\ \left(...
  13. C

    Questions on Remainder & Integer Divisibility

    I have 2 questions. 1)what is the remainder with 100! is divided by 103? explain your answer 2)a = 238000 = 2^4 x 5^3 x 7 x 17 and b=299880 = 2^3 x 3^2 x 5 7^2 17. Is there an integer so that a divides b^n? if so what is the smallest possibility for n? the first one i have no...
  14. I

    Divisibility Test for 11 - Learn How to Check

    Hello I would like to know how to determine whether a number is divisible by 11 or not... say 209. I know the divisibility rules from 2 to 10... but how about 11?
  15. F

    Understanding Divisibility: Exploring Naoki Sato's Number Theory Notes

    I am reading Naoki Sato's notes on Number Theory: http://donut.math.toronto.edu/~naoki/nt.pdf I am on page 2, and doing Example 1.1... "Let x and y be integers. Prove that 2x+3y is divisible by 17 iff 9x+5y is divisible by 17." There's ALREADY A SOLUTION on the book, but I do not...
  16. C

    Proof by Induction and divisibility

    How would I go about proving that 8^n - 3^n (n >= 1) is divisible by 5 using mathematical induction? I tried this but I do not think it is right: First, prove that 8^1 - 3^1 is divisible by 5. 8^1 - 3^1 = 5, which is divisible by 5. Second, prove that 8^(k+1) - 3^(k+1) is divisible by 5 if...
  17. Moni

    Divisibility Testing for Prime Numbers

    We've seen divisibility testing for different numbers...for 2,3,4,5,7,11... But now I want to know is there any way to find divisbility with any prime number? Suppose, how can I say 12783461236 is divisible with 97 or not?
  18. W

    Divisibility of c by a and b but not ab .

    Divisibility of "c" by "a "and "b" but not "ab". Hello, I am having trouble with this question: i) Give an example of three positive integers a,b,c such that a|c and b|c but ab does NOT divide c. ii) In the situation of part (i), is there a condition that guarentees that if a|c and...
  19. W

    Proving Divisibility: A Corrected Proof and Tips for Improvement

    Hello, I am supposed to prove or disprove this statement: Let m,d,n,a be non-zero integers. If m = dn, and if m|an, then d|a. I had a proof but I made an error. Stay tuned for my revised proof. Ok! Here is my corrected proof: By definition: An integer "a", is a...
  20. Ivan Seeking

    Proof for infinite divisibility?

    The thread “Sorites Heap Paradox” brought the following thought to mind. Quantum mechanics may not answer the infinitely divisible question in the way that one would expect. Normally we think of discrete units here, but consider this: I read that at the University at Boulder [I think] an...
Back
Top