Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

If it took eight men ten hours to build a wall, how long would it take four men to build it?

A man dies of old age on his 25 birthday. How is this possible?

Can you solve the photo plexer logic ?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.

Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?

Replace the question mark with the correct number below.

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

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?