When we see 2 but call 10?

Prove that the below maths equation is true.

8 + 8 = 91

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?

I can write cow in 13 letters.

Can You?

Why do you find that most of the buildings are deprived of the 13th floor?

You bought me for dinner but never eat me. What am I?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

What kind of storm is always in a rush?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

What part of the chicken has the most feathers?