Can you make four (4) nines (9) equal 100?

Christina is practising her dance steps along with her friends. In a particular sequence, all of them form a row. At that point, Niharika is standing in the 4th position from either end of the row.
Can you find out how many girls are practising together?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

I cannot talk, but I always reply when spoken to. What am I?

John was drowned by he was not wet. How?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

I can be cracked, made, told, and played. What am I?

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?

Can you count the number of quadrilaterals in the picture below?