Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

What is black when you buy it, red when you use it, and gray when you throw it away?

John was piloting a plane behind a car but was never able to overtake it. Why?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

What Does this text mean:

important=important

On a bright sunny day, two fathers took their son fishing in the lake. Each man and son were able to catch one fish. When they returned to their camp, there were only three fishes in the basket. What happened?

PS: None of the fish were eaten, lost, or thrown back.

You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which.
There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it.
You can, however, ask one robot one question. The problem is one robot always tells the truth, the other always lies and you don't know which is which.
What is the question you ask?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?