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Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
Liver spots have nothing whatsoever to do with the liver. They are a type of freckles commonly seen in older adults who have been out in the sun without sufficient sunscreen.
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
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.
Asthma is the most common chronic childhood disease in the world. Most children who develop asthma have symptoms before they are 5 years old.
![Hyperopia (farsightedness). In the uncorrected top figure, the image would come into focus behind th](https://biology-forums.com/gallery/47/medium_14755_27_08_12_12_24_59_82001466.jpeg)
![Placenta previa. The condition is caused by the development of the placenta over the cervical canal,](https://biology-forums.com/gallery/47/medium_14755_16_10_12_12_29_59_94522485.jpeg)