Meaning of perfect numbers. A perfect number: a number is perfect when the sum of its divisors (except the number itself) equals the given number. Theorem connecting perfect and prime numbers. 6 : The divisors of 6 are 1,2,3 & 6.
Â­A watershed is an area of land that feeds all the water running under it and draining off of it into a body of water. It combines with other watersheds to form a network of rivers and streams that progressively drain into larger water areas. Topography determines where and how water flows.Ridge tops surrounding a body of water determine the boundary of a watershed. Imagine turning an open umbrella upside down in the rain.he umbrella is like a watershed; it collects everything that falls into it. Waterways within the watershed all feed into that main body of water, which could be a river, lake, or stream. The beginnings of a water source are called headwaters.
A watershed includes not only the land within its boundaries but also the surface water of lakes, streams and wetlands as well as the groundwater moving beneath the surface. Watersheds vary from the largest river basins to just a few acres in size. Watersheds are natural systems that link the land and water resources and the living organisms, including people, within its boundaries. How we live on the land affects the quality and quantity of water resources within the watershed.