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

If Bihan is 10, Anirudha is 20, and Kim and Seal are both 5, but Rikold is 10, how much is Kenniger by the same trend?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Count the number of triangles in the picture below:

What is the below Rebus indicate?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

12345 a famous South Indian actor
567 is a path in jumbled form
8 & 10 are same letters
9 is one among the first six alphabets.
WHO AM I?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

How many triangles are there on the puzzle below?