If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

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

Find the 8 in the below-given Image.

Complete the table series riddle by finding the number that can replace "??".

One night, a woman receives a call from the police. They tell her that her husband was murdered and that she should come to the crime scene as soon as possible. The woman drops the phone, shocked, and drives 20 minutes to the crime scene. As soon as she reaches the crime scene, the police arrest her and she is convicted of murder. How do the police know she committed the crime?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

What makes this number unique: 8,549,176,320?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

Count the Triangle in the figure given below: