Question

How can I tell if two numbers are divisible by the same number(s)??? for example 123 and 492?

My teacher said something about adding the numbers and the total is the number that can divide into the number.

e.g 123 = 6 so 123 should be divisible by 6 right?

Answer 1

No... I won't agree
I will prefer to use prime factorization...
123 = 3 x 41
492 = 2^2 x 3 x 41

Answer 2

so both 123 and 492 are divisible by 41.

Answer 3

123 is not divisible by 6. actually the shortcut to check for divisibility by 6 is to see if the number is even before adding the digits to see if they equal 3 or a number divisible by 3 (like 6 or 9)

Answer 4

Yes both are divisible by 41

Answer 5

In fact both r divisible by 123 !!! (3 x 41)

Answer 6

Have you got any tips on reconsigning divisibility? @ Harkirat

Answer 7

@strawberry_militia
Learn your divisibility rules for 2,3,4,5,6,7,8,9,10,11
also remember if a number is divisible by two co-prime numbers A and B, then it is divisible by A*B

eg 180 is divisible by 3 and 180 is divisible by 5
so 180 is also divisible by 15 (3*5)

Answer 8

Are u familiar with above rules????

Answer 9

just memorize every single possible factorization of every single positive integer

Answer 10

prime factorization*

Answer 11

no agdg, i think that is not the way to go about it....
knowing your divisibility rules is the way to go.......

Answer 12

well, use the divisibility rules to factor 7919.

Answer 13

he is not asking about factorisation..
he is asking how to check if a number is divisible by another number....

Answer 14

true

Answer 15

but isn't prime factorization a way to find what a number is divisible by?

Answer 16

but don't you need to recognise divisibility to be able to prime factorize?

Answer 17

right :P

Answer 18

@strawberry_militia

I have found a website where rules r given, hope it helps.....

http://www.mathsisfun.com/divisibility-rules.html

just visit this site, try the rules out, copy them and take some numbers and practice on them.........
Best of luck..........☺


@agdg
u also pls visit the above website and you'll understand what I am saying....
by this method u can quickly check if a number is divisible by 15, 35 etc.

Answer 19

those wont help you find out if 5137367 is divisible or not

Answer 20

also for prime fact u need to quickly decide whether a number is divisible by a prime number or not.....

Answer 21

divisible by what????

Answer 22

exactly

Answer 23

@agdg
U do not seem to have understood the discussion at all.....
we r talking about divisibility of numbers and for that you need two numbers - dividend and divisor
you r giving one number and then saying "exactly" when I ask by which number u want to check divisibility.........

as i wrote, visit the website and maybe you will follow what we r talking about.......

checking for divisibility by a number is required for prime factorisation and not vice versa..