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

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

Can you find out the total number of triangles in the given figure?

You are on a Boat in the mid of a river. You have two cigarettes with you. One of these two you have to light, how will you light the cigarette?

If we tell you that there is a relation between the numbers and letters in the given figure, can you analyze it and find the missing letter in the last box?

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

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?