Why Aeroplane windows are round?

What does this rebus mean?

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You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

How do you go from 98 to 720 using just one letter?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

You have two bottles of pills marked with labels A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.

While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.

You cant throw away the expensive pills. What will you do now?

By moving just one matchstick, you need to make the below statement true. Can you do it?

What always comes into a house through the keyhole?

What is Luis Suarez's (Soccer Player) favorite tea?

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.