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?

Can you decipher the below rebus?

PBLUESAISNUERSES

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

Look at me. I can bring a smile to your face, A tear to your eye, Or even a thought to your mind. But, I can't be seen. What am I?

Can you find out the total number of triangles in the given figure?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

What work can one never finish?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A clock loses 10 minutes each hour. If the clock is set correctly at noon, what time is it when it reads 3 PM?

In one of the popular batman series movie "Batman Forever", there was a riddle that goes like "Tear me off and then scratch my head and I was red then and now I am back. Who am I?