Can you solve the below algebraic mathematical equation?

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

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

Can you make four (4) nines (9) equal 100?

There are a hundred statements.

First person says: At least one of the statements is false.

Second person says: At least two of the statements is false.

Third person says: At least three of the statements are false.

Fourth person says: At least four of the statements are false.

..

..

..

Hundredth person says: At least a hundred of the statements are false.

Analysing it, how many statements do you think are false and how many are true?

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?

Can you find the six hidden animals in the picture below?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?