Replace the question mark with a number
MATH PUZZLE: Can you replace the question mark with a number?Correct answers: 371
The first user who solved this task is Djordje Timotijevic.
#brainteasers #math #riddles
Ballpen in space
When NASA first started sending up astronauts, they quickly discovered that ballpoint pens would not work in zero gravity.
To combat the problem, NASA scientists spent a decade and $12 billion to develop a pen that writes in zero gravity, upside down, underwater, on almost any surface including glass and at temperatures ranging from below freezing to 300 C.
The Russians used a pencil.