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

You’re out on the water and see a boat filled with people. You look away for a second and look back again, but this time you don’t see a single person on the boat. Why? Hint: The boat did not sink.

It is raining today at 11:59 am. What is the probability of sunny weather after 72 hours?

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

John was born on March 5, 1970, in Delhi, India. Jacob was born 25 days before John. The year when they took birth, Republic Day fell on Monday.

Can you find out on what day was Jacob born?

If you paint a brown house white it will become a white house. If the stoplight changes from red to green, then the light is green. So, if you throw a white shirt into the Red Sea, what will it become?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

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

How Come ??