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?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

How many triangles are there in the picture below?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

How can I get the answer 24 by only using the numbers 8,8,3,3?

You can use the main signs add, subtract multiply and divide.

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).