Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

O_er_t_o_

Complete the missing letters of the given word.

Why is a river so rich ?

What has one eye, but can’t see?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

Below, you can see some coding:
January = 1017
February = 628
March = 1335
April = 145
May = 1353
June = 1064
July = 1074
August = 186

Now deciphering the way it has been coded, can you find out how September will be coded?

You throw me out when you want to use me and you take me in when you don't want to use me.

Who Am I?

Name a key which is hardest to turn.

What Deficiency does the below rebus represent?

VIT_MIN

Find the last number in the series below:

voN luJ yaM raM ---