Find number abc
If a99bb - 18717 = 5118c find number abc. Multiple solutions may exist.Correct answers: 30
The first user who solved this task is Nílton Corrêa de Sousa.
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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.