What number when divided in half becomes zero?

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?

What does the below rebus riddle means?

I shave every day, but my beard stays the same. What am I?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

I have Rs.50 and I spend it in the way as below.

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

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?

I am a word of 12 alphabets.

* Alphabets 12, 4, 7, 2, 5 : Eastern beast of burden
* Alphabets 1, 8, 10, 9 are street made famous by Sinclair Lewis.
* Alphabets 11, 3, 6 are past.

On whole it means a person suffering from delusions of greatness.

What Is it ?

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?