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

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?

Can you find out the remainder when 3^300 is divided by 5?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

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

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?