Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

What always comes into a house through the keyhole?

You see me once in June, twice in November, and not at all in May. What am I?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

What does the below mathematical rebus mean?

How many times in a given day, minutes and hour clock comes in a straight line ?

Solve the rebus riddle in the picture below.

Which is the rope you never skip with?