What to do after 9th ?

The book "one Indian Girl" is the 7th fictional novel and the 9th overall novel written by the Indian author………?

In a potentiometer, the null point is received at 7th wire. If now we have to change the null point at 9th wire, what should we do?

Sangeeta remembers that her father's birthday was certainly after 8th but before 13th of December. Her sister Natasha remembers that their father's birthday was definitely after 9th but before 14th of December. On which date of December was their father's birthday?

If in a GP, 5th term and the 12th term are 9 and (1)/(243) respectively, find the 9th term of GP.

If the 9th term of an AP is zero, then prove that its 29th term is twice its 19th term.