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The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.