Can you solve below mathematical equation?

2^1234 - 2^1233

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Which letter of the alphabet has the most water?

Can you decipher the below rebus?

PBLUESAISNUERSES

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

In a school, 280 students studied chemistry, 254 students studied physics and 280 students studied biology.

97 students studied chemistry as well as physics, 138 students studied physics as well as biology and 152 students studied chemistry as well as biology.

73 students studied all the three branches.

Can you find out the total number of students?

What demands an answer, but asks no questions

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which.
There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it.
You can, however, ask one robot one question. The problem is one robot always tells the truth, the other always lies and you don't know which is which.
What is the question you ask?