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Did you know?
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Did you know?
The horizontal fraction bar was introduced by the Arabs.
Did you know?
The human body produces and destroys 15 million blood cells every second.
Did you know?
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
Did you know?
In 1844, Charles Goodyear obtained the first patent for a rubber condom.