How many times in a given day, minutes and hour clock comes in a straight line ?

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

What does below chemistry rebus means?

Three brothers Jacob, John, and James live in Mexico City. The product of the ages of these brothers is 175. Jacob and John are twins. How old is James?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

What happened when the wheel was invented?

When 99 is considered higher than 100?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

No one wants to have it, but if one got it, he does not want to lose it. What is It?