Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

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

It can be easily calculated that the digits 0 to 9 can be arranged into 3628800 distinct ten-digit numbers.

But do you know how many of these numbers are prime?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

Why 1729 is a magic number? Answer Logically.

How can you take 2 from 5 and leave 4?

What demands an answer, but asks no questions

A monk has a very specific ritual for climbing up the steps to the temple. First, he climbs up to the middle step and meditates for 1 minute. Then he climbs up 8 steps and faces east until he hears a bird singing. Then he walks down 12 steps and picks up a pebble. He takes one step up and tosses the pebble over his left shoulder. Now, he walks up the remaining steps three at a time which only takes him 9 paces. How many steps are there?

The more of this there is, the less you see. What is it?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?