Can you replace the question mark with the correct number?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

Count the number of balls in picture below:

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

Accidentally, two trains are running in the opposite direction and enter a tunnel that is 200 miles long. A supersonic bird that has fled the lab and taken shelter in the tunnel starts flying from one train towards the other at a speed of 1000 mph. As soon as it reaches the second train, he starts flying back to avoid collision and meets the first train again at the other end. The bird keeps flying to and fro till the trains collide with each other.

What is the total distance that the supersonic bird has traveled till the trains collided?

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

Katrina wants to go on a date and prefers her date to be tall, dark and handsome.

Of the preferred traits - tall, dark and handsome - no two of Shahrukh, Ajay, Salman and Akshay have the same number.
Only Shahrukh or Akshay is tall and fair.
Only Ajay or Salman is short and handsome.
Shahrukh and Salman are either both tall or short.
Ajay and Akshay are either both dark or both fair.
Who is Katrina's date?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

what does this below rebus represent identXQQQQQME

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?