How can you take 2 from 5 and leave 4?

You are a cab driver who pools passengers. You pick 3 people from a destination and drop 1 after an hour. 2 people climb aboard at the same time and you drop 3 at the next destination. After some time, you pick 2 passengers only to drop 1 after a short distance where 3 more passengers climb up the cab. You leave the rest of the passengers one by one to their destination and then come back home.

Can you tell the eye color of the cab driver?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Prove that twice of ten is the same as twice of eleven.

Six people park their car in an underground parking of a store. The store has six floors in all. Each one of them goes to a different floor. Simon stays in the lift for the longest. Sia gets out before Peter but after Tracy. The first one to get out is Harold. Debra leaves after Tracy who gets out on the third floor.

Can you find out who leaves the lift on which floor?

There is something which you can be arrested for attempting but not for successfully completing.

One day, I thought of ways that can be used for creating a palindrome. So I decided that I will turn into a larger number by adding the reversed digits to the original number and keep doing it till I finally obtained a palindrome.

I am not sure if this process will always result in a palindrome eventually but I was able to produce a four-digit palindrome. Can you guess my starting number?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

If a wheel has 54 spokes, how many spaces are there between the spokes?

Spot 5 differences in two Christmas tree below: