Cristina was born in 1888. She just had her 30th birthday today how did that happen?

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 ?

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?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

What number do you get when you multiply all of the numbers on a telephone's number pad?

In a football game, Christina defeated Teresa by 2 - 0 but no man from either side scored. How can this be possible?

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?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Manish and Manoj play 5 games of chess.
Both Manish and Manoj win the exact same number of games. There is no tie at all.

How?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.