I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Name a key which is hardest to turn.

What am I?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

You are given with the following sum. Each of the letters can be decoded as a digit. If we tell you that D = 5, then can you solve it entirely?

DONALD
+GERALD
=ROBERT

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

Using eight eights and addition only, can you make 1000?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.

What is it?

Replace the question mark with the correct number in below Picture: