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

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

Asked by Neha on 21 Apr 2025


Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

Asked by Neha on 05 Aug 2023

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Asked by Neha on 10 Mar 2024


Make a sentence consisting of three words that have the whole alphabet.

Asked by Neha on 11 Dec 2025

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

Asked by Neha on 22 Mar 2025

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

Asked by Neha on 04 Jul 2023


What goes up but never comes down?

Asked by Neha on 11 May 2022

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

You need to pick one entry from pot A and one from pot B to have a perfect match. Can you do it?

Football World Cup 2014

Asked by Neha on 22 Aug 2021


A man was convicted of a minor offence in Akbar court. Akbar decided to give him a chance. He asked him to give a statement. If the statement is true, he will be killed by lions and if it is false, he will be killed by trampling of wild elephants.

The convicted person requested help from Birbal and since the crime was not a big one, Birbal decided to help him. Whatever Birbal suggested impressed Kabir and he let the convicted person go.

What did Birbal suggest to the person?

Asked by Neha on 10 May 2021

Hot Articles

Amazing Facts

Crossword

The day before the 1996 U.S. presidential election, the NYT Crossword contained the clue “Lead story in tomorrow’s newspaper,” the puzzle was built so that both electoral outcomes were correct answers, requiring 7 other clues to have dual responses.