Can you find out which number multiplied by itself will give the output as 12345678987654321?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

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

I guess 76.8% of readers will like this riddle.

What's the least number of people should read this post?

Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

An octopus has 8 legs. A hippogriff has 6 legs and 2 pairs of wings. A sphinx has 6 legs and one pair of wings. Now we have all 3 kinds and a total of 18 insects in a cage. We have a total of 118 legs and 20 pairs of wings. How many insects do we have of each kind?

What is next number in the pattern below:

131 517 192 123 ?