Can you replace the question mark with the correct number?

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?

1. Where does Easter come from before Valentine's Day?

2. Do you know what is in the middle of Valentine's?

3. What did the lady bee say to the man bee on the occasion of Valentine's Day

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Can you find out the remainder when 3^300 is divided by 5?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

It is a nine-letter word.
The exact opposite of the phrase "friendly and outgoing"
It contains the word "over".
It starts will a vowel.

What is it?

Find the last number in the series below:

voN luJ yaM raM ---

You have a thousand Re. 1 coins with you. You have ten bags with you and you can put any number of coins in each of the bags. The condition is that if someone asks you for any amount between 1 and 1000, you must be able to give that amount by just giving the bag (you are not allowed to open the bag and give coins).

How will you do it?

How can you make number one disappear by adding something to it?