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If 21x = 79x, what is the value of x?




Similar Math Riddles

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


We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

Asked by Neha on 19 Sep 2025

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

Asked by Neha on 15 Dec 2024


Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

Asked by Neha on 29 Jul 2021

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

 Weight of Animals

Asked by Neha on 17 Jan 2024

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

Asked by Neha on 26 Feb 2022


Find three whole, positive numbers that have the same answer when multiplied together as when added together.

Asked by Neha on 01 Jan 2021

I want to fill my bucket using both cold and hot water.
I have two taps for both cold and hot water. The hot water tap fills the bucket in exact 6 hours and the cold water tap fills the bucket in exact 4 hours.
I turn both of them simultaneously but I forgot to turn off another tap which removes the water out of the bucket. This tap can empty the bucket in 12 hours.

How Long will it take to fill the bucket?

Asked by Neha on 30 Sep 2023

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

Asked by Neha on 05 Apr 2026


If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

Asked by Neha on 05 Aug 2025

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