How can you write nineteen in a manner that if we take out one, it becomes twenty?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

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?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

What is both possible and impossible at the same time?

What brings you down but never up?

What work can one never finish?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

The following "Brain Bat" means Slow Down.
S
L
O
W

Using the same logic, can you tell us what does the following Brain Bat means ?
E
V
I
G