How can you make number one disappear by adding something to it?

What is the coolest letter in the alphabet?

An old Woman left INR 33,333 to be divided equally among two fathers and two sons and each was to receive INR 11,111.
How was this possible?

Using exactly three matchsticks, can you divide the area into two equal parts?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

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?

Can you count the number of triangles in the given picture?

What has one eye, but can’t see?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??