Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

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

A letter is hidden in the image in plain sight. Can you spot it in 6 seconds? Test your eye power now!

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

When a clock is observed, the hour hand is at a minute mark and the minutes hand is six minutes ahead of it.

When the clock is observed again after some time, the hour hand is precisely on a different minute mark and the minute hand is seven minutes ahead of it.

Can you calculate how much time has elapsed between the two observations?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

What is the relationship between these matchstick pictures below?

From a pack of 52 cards, I placed 4 cards on the table.

I will give you 4 clues about the cards:

Clue 1: Card on left cannot be greater than the card on the right.
Clue 2: Difference between the 1st card and 3rd card is 8.
Clue 3: There is no card of an ace.
Clue 4: There are no face cards (queen, king, jacks).
Clue 5: Difference between the 2nd card and 4th card is 7.

Identify four cards?

Pooja gave Neha as many Ponds as Neha started with.
Neha then gave Pooja back as much as Pooja had left.
Pooja then gave Neha as back as many Ponds as Neha had left, which left Pooja broke and gave Neha a total of 80 pounds. How much did Pooja and Neha have at the beginning of their exchange?

Can you count the number of quadrilaterals in the picture below?