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Congestive heart failure is a serious disorder that carries a reduced life expectancy. Heart failure is usually a chronic illness, and it may worsen with infection or other physical stressors.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
Hypertension is a silent killer because it is deadly and has no significant early symptoms. The danger from hypertension is the extra load on the heart, which can lead to hypertensive heart disease and kidney damage. This occurs without any major symptoms until the high blood pressure becomes extreme. Regular blood pressure checks are an important method of catching hypertension before it can kill you.
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."