Replace the question mark with the correct number.

How many words can a quill made with the feather of a pigeon write with a 100ml bottle of black ink?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

What does this rebus means ?

PROG WORKRESS

Name a key which is hardest to turn.

Why 1729 is a magic number? Answer Logically.

We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

In an interview, a boy was asked an unusual question 'How two persons sitting with a table in between them can't see each other?' He was unable to reply. Can you?

What does below Rebus say?

XLR8

If two's company, and three's a crowd, then whats four and five ?