A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

An equation has been laid down using a few matchsticks. However, as you can see, the equation is not correct. Can you correct the equation if you are allowed to add or remove 5 matchsticks?

Why is the Hole below a Lock?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

A man was telling some of his war stories to his grandchildren.
"When the World War I was on the verge of end, I was awarded for my bravery for I had saved a group of my men." He coughed and then added, "When we were fighting in northern France, an enemy soldier threw a grenade at us. Before it could explode, I picked it up and threw it away. For my act of bravery, right before the war ended, A General gave me a sword engraved with the words "Awarded for Display of Bravery and Heroism in World War 1"."

Hearing this, one of the grandson spoke up. "Grandpa, this is not a true story. It can"t be true!"

The truth is that it was not. How did the grand children know it?

What does below pictogram mean?

Move four matchsticks to the below square to form three squares?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

What month of the year has 28 days?

What has many keys but can’t open a single lock?