Black Changes its Colour

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




Similar Riddles

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

Asked by Neha on 03 Mar 2024


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

Asked by Neha on 27 Aug 2021

Can you find out the total number of triangles in the given figure?

Triangle Angle

Asked by Neha on 12 Mar 2024


Which is Odd One Out and why?

4377

3954

9862

8454

9831

Asked by Neha on 09 Jan 2024

There are four people in a house. A fireman, an athlete, an old woman, and a drunk guy. The house catches fire and before the fact is known, it is too late. All they know is that the entire house is in flames and it will collapse exactly after twelve minutes. Now they can move out of the house but for that, they will have to pass the hallway which is entirely blazing with flames. Thus to move, one must carry a fire extinguisher to keep the flames away. Seeking the burnt wooden floor, only two people can run through that hallway at one time. But for others to go, one must return back with the fire extinguisher. The fireman is trained for such tasks and can run through the hallway in a minute. The athlete can make it in a couple of minutes. The old woman can run slowly and will cover the hallway in four minutes. The drunk guy will take five minutes to run through it. If all of them can make it through the hallway in twelve minutes, all of them will be saved. When two move together, they will run at the speed of the slower ones.

How will all four of them manage to run to safety?

Asked by Neha on 02 Jun 2023

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

Asked by Neha on 17 Jun 2025


If we tell you that there is a relation between the numbers and letters in the given figure, can you analyze it and find the missing letter in the last box?

Relationship in Numbers and Letters

Asked by Neha on 11 Jun 2023

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Asked by Neha on 17 May 2021

Replace the question mark with the correct number below.

Tree Problem

Asked by Neha on 19 Mar 2024


There are three boxes. One is labeled "APPLES" another is labeled "ORANGES". The last one is labeled "APPLES AND ORANGES". You know that each is labeled incorrectly. You may ask me to pick one fruit from one box which you choose.

How can you label the boxes correctly?

Asked by Neha on 07 Sep 2021

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Amazing Facts

Out of the Box

The phrase “thinking outside the box” was popularised from the solution to a topographical puzzle involving 9 dots in a box shape.