81 x 9 = 801. What must you do to make the this equation true?

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

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

What does this mathematical rebus means ?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

While house hunting in London, I came across a very good leasehold property Discussing the lease the landlady told me:

'The property was originally on a 99 years lease and two-thirds of the time passed is equal to four-fifths of the time to come. Now work it out for yourself and see how many years are to go!

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?