Remove two matchsticks to make the below equation correct.

No matter how little or how much you use me, you change me every month. What am I?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

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

A girl was standing near the window thinking something. All of a sudden she decides something and throws something out of the window. She dies very soon after throwing it. She was perfectly healthy and had no disease or allergy. No one killed her and she did not commit suicide.

Can you think of any possible explanation that is logical as well for what happened there?

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

What four weights can be used to balance from 1 to 30 pounds?

You have a basket containing ten apples. You have ten friends, who each desire an apple. You give each of your friends one apple.
Now all your friends have one apple each, yet there is an apple remaining in the basket.
How?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

Count the number of balls in picture below: