The criterion of divisibility by 9 is very similar to the criterion of divisibility by number 3. Do you remember this criterion? If not, access the article Divisibility by 3.
To find out if a given number is really divisible by 9, we'll also look at all the digits in that number. Similar to the divisibility by 3 criterion, we should add the digits and check if this sum is divisible by the number 9.
Therefore, we can determine what is the divisibility criterion by 9:
"In order for a number to be divisible by the number 9, the sum of the digits of that number must be divisible by 9".
For example, the sum of the digits of the number 63 is equal to 9, which, in turn, is divisible by 9. We can then say that the number 63 is divisible by 9.
Let's look at an example with a number with a larger number of digits.
"Check the divisibility of the number 32463 by number 9"
As we saw in the divisibility criterion, we must add the digits and check if this sum is divisible by 9.
Checking if the number 18 is divisible by 9 is very easy after all 18=9x2.
This process facilitates the verification, after all, it is easier to verify the divisibility of the number 18 than of a number with as many digits as 32463.
