Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

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?

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

What Word am I Looking For ?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?