Question

Check whether $876$ and $345$ are divisible by $3$? Also check whether $3$ divides the difference of $876$ and $345$?

Answer 1

For Divisible by 3, we need to check if the sum of the digits is divisible by 3.
Now, Let us use the above rule as follows $:-$
For $876$, $8+7+6=21$ which is divisible by $3$.
Similarly, For $345$, $3+4+5=12$ which is divisible by $3$.
Therefore, Both numbers are divisible by $3$
Now, Difference $\to 876-345=531$
Applying the same Rule as above,For $531$, $5+3+1=9$ which is divisible by $3$.
Therefore it is divisible by $3$