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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Today, nearly 8 out of 10 pregnant women living with HIV (about 1.1 million), receive antiretrovirals.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Cyanide works by making the human body unable to use oxygen.
There are 20 feet of blood vessels in each square inch of human skin.
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