What occurs twice in a week, once in a year but never in a day?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

Three friends named Mr. Black, Mr. Yellow and Mr. Green enter a pub on a weekend night. They are wearing either a Black, Yellow or Green shirt.

Mr. Yellow says to them, 'Did you notice that we all are wearing different color shirts than our names?'

To this, the man who was wearing the Green shirt said. 'Wow, thats right.'

Can you identify who is wearing which colour shirt ?

The barber of Town shaves all men living in the town. No man living in the town is allowed to shave himself. The barber lives in that town. Who then shaves the barber of the town?

What is the next number in the series?

15 29 56 108 208 ?

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

Why Aeroplane windows are round?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

What is the next number in this matchsticks series riddle?