How many elements in $X$ are divisible by $3$? Consider the set $X = ${$300, 301, 302, . . . , 29999, 30000$} (the set of all integers from $300$ to $30, 000$ inclusive.) You do not need to simplify the numeric answers.
How many elements in $X$ are divisible by $3$?
This is my answer. I just want to double check I'm doing this correctly. 
$10000-100+1$
Is that right?

Upto $30,000\to \frac {30000}{3}$ numbers, upto $300\to \frac {300}{3}$ numbers, subtract them, add back $1$ to account for the "$300$" lost, and you get $10000-100+1$. Yes, you are right.
