During which month do people sleep the least?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

My sock drawer has 26 blue socks, 13 pink socks, 33 green socks, and 12 red socks, how many socks would I have to pull out in the dark to be sure I had a matching pair?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

What does it mean?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?