What's the only room from which no one can enter or leave

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

The current time can be represented by below textual rebus.

0
=========
B.Sc
LLB

Can you tell us the current time?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?

Three people are in a room. Ronni looks at the Nile. The Nile looks at Senthil. Ronni is married but Senthil is not married. At any point, is a married person looking at an unmarried person? Yes, No or Cannot be determined.

How can you write nineteen in a manner that if we take out one, it becomes twenty?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

Identify the movie name through below Rebus containing Pi Mouse and coconut tree..