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Did you know?
The horizontal fraction bar was introduced by the Arabs.
Did you know?
It is believed that humans initially contracted crabs from gorillas about 3 million years ago from either sleeping in gorilla nests or eating the apes.
Did you know?
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Did you know?
The familiar sounds of your heart are made by the heart's valves as they open and close.