What occurs twice in a week, once in a year but never in a day?

The more it dries, the wetter it becomes. Can you tell what it is?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

Which is the smallest number that you can write using all the vowels exactly once?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?