Question

How many four digit numbers are there which are divisible by $2$.

Answer 1

According to the problem,

the number divisible by $2$ are

$1000,1002,1004,1006,...........,9994,9996,9998.$

Every $10$ numbers there are $5$ even numbers.

and for $100$ number we have $50$ even numbers.

So, Every $1000$ number there $500$ even numbers.

And there are $10$ $1000s$ in $1000$ to $9999$

Hence there are

$5000(500\times 10)$ even numbers.