Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

Why is the Hole below a Lock?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

Which is the correct shadow of the bird?

Spot the cat in the picture below

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Replace the question mark with the correct number below.

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

A train leaves from point A for point B at 80 mph. After half an hour, another train leaves from point B for point A at 60 mph.

Which of the trains will be farther from point A when they meet ?

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?