One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

How many times can you subtract the number two from the number fifty?

Nodes are shown below and you need to connect them based on the following rule: Every node can be connected to the number of nodes inside them, i.e. the first node there is a value of 1 which indicates that the first node can connect to exactly one node only.Can you do it?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

No matter how little or how much you use me, you change me every month. What am I?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

How many times can you subtract the number 5 from 25?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?