Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

What number do you get when you multiply all of the numbers on a telephone's number pad?

I start and end with 500 and carry a 5 in my heart. But I require the first letter and the first number to be complete. I am the name of a King.

Who am I ?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

What has lots of eyes, but can’t see?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

Find the next number in the series below

21 32 54 87 131 ?