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Did you know?
The horizontal fraction bar was introduced by the Arabs.
Did you know?
The B-complex vitamins and vitamin C are not stored in the body and must be replaced each day.
Did you know?
There are more nerve cells in one human brain than there are stars in the Milky Way.
Did you know?
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).
Did you know?
Acute bronchitis is an inflammation of the breathing tubes (bronchi), which causes increased mucus production and other changes. It is usually caused by bacteria or viruses, can be serious in people who have pulmonary or cardiac diseases, and can lead to pneumonia.
![This engraving by William Russell Birch shows Congress Hall (left), which was occupied by Congress f](https://biology-forums.com/gallery/47/medium_374628_16_08_15_9_52_06_222501221.jpeg)
![A passenger train crosses Stony Creek Bridge in the Rocky Mountains in 1878. Railroads were importan](https://biology-forums.com/gallery/47/medium_27_24_08_15_1_27_03_22389406.jpeg)