There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

Different lights make me strange by changing me into different sizes. What am I?

On my way to St. Ives I saw a man with 7 wives. Each wife had 7 sacks. Each sack had 7 cats. Each cat had 7 kittens. Kittens, cats, sacks, wives. How many were going to St. Ives?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

what's the probability of getting a king or a queen from a pack of 52 cards?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?