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Author Question: If combustion air openings pass through horizontal ducts with 4,000 BTU input, how large should the ... (Read 30 times) |
Vaccines prevent between 2.5 and 4 million deaths every year.
Approximately 15–25% of recognized pregnancies end in miscarriage. However, many miscarriages often occur before a woman even knows she is pregnant.
It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."