What word is pronounced the same if you take away four of its five letters?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

How many Watermelons are there in the below picture?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?

Count the number of triangles in the picture below:

If eleven plus two equals one, what does nine plus five equal?

What is the below Rebus indicate?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

I’m tall when I’m young, and I’m short when I’m old. What am I?