What is more useful when it is broken?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Can you place six X (crosses) in below board without making three in a row in any way ?

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?

Replace the question mark with the number below given a simple math problem.

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?