Count the Triangle in the figure given below:

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

What happened when the wheel was invented?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

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?

A spy was in Canada trying to steal insider information on how to set up new Maple Syrup factories in their country. He was introduced to the operations manager of the biggest factory in Canada. However, the manager was suspicious and decided to test him with a question before he trusted him. So he asked, “What would you be sure to find in the middle of Toronto?” The spy thought fast and came up with an answer for the manager. What was his answer?

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

which number am I?

Find the value of "?" in the ball picture Riddle below:

Next Number in the Series,

5, 16, 49, 104, ?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?