Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

One day, all the courtiers from Akbar's court were gathered in the assembly hall when one of them told the Emperor that all his valuables had been stolen by a thief the previous night.
This shocked the Emperor to his core as the place where that courter stayed was the most secured in the kingdom. The Emperor thought that it is not at all possible for an outsider to enter into the courtier's house and steal the valuables. Only another courtier could commit this crime. He quickly called Birbal to identify the thief.
Birbal thought for a while and successfully solved the mystery by identifying the thief in just one statement.
What did Birbal say?

What type of tree can I carry in my hand?

Two old friends, Jack and Jill, meet after a long time, and discussing as:

Jack: Hey, how are you, man?

Bill: Not bad, got married and I have three kids now.

Jack: That's awesome. How old are they?

Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.

Jack: Cool..But I still don't know.

Bill: My eldest kid just started taking piano lessons.

Jack: Oh, now I get it.

How old are Bill's kids?

Why do we preferably have round manhole covers and not square ones?

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?

What does this say?

XLR8

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?