What number is divisible by 3 6 and 9?

Answer 1

yes

* * * * *

Absolutely not! If it is divisible by 9 it must be divisible by 3.

Here, if you want it, is a proof:

x is divisible by 9 implies that x = 9*y for some integer y.

Now 9 = 3*3, so writing 3*3 instead of 9 gives

x = (3*3)*y

so, by the associative property of multiplication,

x = 3*(3*y)

and then, by the closure of multiplication of integers, 3*y is also an integer. Say, z, for example.

That is to say, x = 3*z

which is equivalent to saying that x is divisible by 3.

Answer 2

Because 9 is divisible by 3, this is like the rule where if a number is divisible by 2 and 3 it is also divisible by 6.

Answer 3

Because any number that has 6 as a factor will also have the factors of 6 as factors.

Answer 4

Multiples of multiples of three are also multiples of three.

Answer 5

3, 6, 9, 12, 15 and just keep adding three until you get to infinity.

Answer 6

No. 5 and 7 are odd numbers.

Answer 7

The set of multiples of 9.

Answer 8

18

Answer 9

because three times one equals three

Answer 10

72