It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

I know a nine-letter word having only one vowel.
Do you ?

Name a key which is hardest to turn.

I am a three digit number.
My tens digit is five more than my ones digit.
My hundreds digit is eight less than my tens digit.
What number am I?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

A newspaper is supposed to have 60 pages.Pages 14 and 21 are missing from the newspaper.

Can you tell me , Which other pages won't be there as well ?

In the image given, you can find several triangles. Can you count them all?

I know a 5-digit number having a property that With a 1 after it, it is three times as large as it would be with a one before it.

Guess the number?