If two's company, and three's a crowd, then whats four and five ?

When it's bad luck to meet a black cat?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

Find the smallest sentence with all the English alphabet.

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.

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

What does below rebus means ?

The answer I give is yes, but what I mean is no. What was the question?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT