Ask unlimited questions for free
The horizontal fraction bar was introduced by the Arabs.
There are 20 feet of blood vessels in each square inch of human skin.
The strongest synthetic topical retinoid drug available, tazarotene, is used to treat sun-damaged skin, acne, and psoriasis.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
For a complete list of videos, visit our video library