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

What's a single-digit number with no value?

Can you write down eight eights so that they add up to one thousand?

A Shopkeeper collects 71 rupees in the form of 20 paisa and 25 paisa.
He collects a total of 324 coins.

Can you tell me how many number of 20-paisa and 25-paisa he got?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

I am an eight letter word and I am a computer terminology.
The second, third and fourth letters make an animal.
The fourth, fifth, sixth, seventh and eighth letters make a weapon.
The first, second, third and fourth letters can be taken as an outcome of any exam.
The fifth, sixth, seventh and eighth letter combine to form a high end typing software.

Can you tell who am I ?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

Through your logical capabilities, can you make 7 an even?

Find the missing letter in the last circle logically in the given below picture.