Maths Logic

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




Similar Riddles

500 women soldiers are arranged in an array of ten rows and fifty columns in accordance with their respective heights. Now, the tallest woman from each row is asked to move out in the front. From them, the shortest one is labelled as Alpha. They are then asked to resume their original position.

Now, the shortest woman in each column is asked to come out in front. The tallest among them is labelled as Beta.

Can you find out if Alpha will be taller or Beta?

Asked by Neha on 16 Sep 2025


As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

Asked by Neha on 23 Apr 2023

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

Odd one out Doraemon picture riddle

Asked by Neha on 19 Apr 2021


Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

Asked by Neha on 26 Jul 2025

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Asked by Neha on 22 Jan 2024

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

Fun With Matchsticks

Asked by Neha on 13 Dec 2023


The more of this there is, the less you see. What is it?

Asked by Neha on 19 May 2022

John is found dead in a bare field. Nobody killed John,
John did not commit suicide.

Inspector Jacob found a bag just a few meters away from John which could save his life. What was in the bag?

Asked by Neha on 04 Dec 2025

By using all numbers, i.e. 123456789 and subtraction/addition, operators number 100 can be formed in many ways.
Example: 98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100

But if we add a condition use of the number 32 is a must. Then there are limited solutions.
One of such solution is: 9 - 8 + 76 + 54 - 32 + 1 = 100

Can you tell me any other solution?

Asked by Neha on 10 Aug 2024


The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Asked by Neha on 15 Dec 2024

Hot Articles

Amazing Facts

Crossword puzzles

In the 1920s, people feared that crossword puzzles would contribute to illiteracy.