There is an English word that can be used up to four times in a row without modifying the spelling and form a valid grammatical sentence.

Do you know what word is that?

Replace the question mark with the correct number below.

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

Why do you find that most of the buildings are deprived of the 13th floor?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

What runs around the whole yard without moving?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?