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numeration systems and numbers
More than 5,000 years ago an Egyptian ruler recorded, perhaps with a bit of exaggeration, the capture of 120,000 prisoners, 400,000 oxen, and 1,422,000 goats. This event was inscribed on a ceremonial mace which now is in a museum in Oxford, England.
 | measurement
The branch of arithmetic that is concerned with measurement of length, surface, and volume is called mensuration. Mensuration deals with so-called geometrical figures, such as squares, triangles, circles, cubes, spheres, and cylinders. Measurements of these figures are much used in surveying ...
| radiation
The warmth of the sun, an X ray taken in a doctor's office, the sound of a guitar, and electricity generated in a nuclear power plant all have one thing in common. They are results of radiation. Radiation is the movement, or propagation, of energy from one place to another. From a human ...
| percentage and interest
The expression of part of a whole in terms of hundredths is known as percentage. The term percent comes from the Latin word centum, meaning “hundred.” Thus, the whole of something is always 100 percent (100%), or 100 hundredths.
| space travel
“That's one small step for [a] man, one giant leap for mankind.” With those words, on July 20, 1969, United States astronaut Neil A. Armstrong stepped from the lunar landing vehicle Eagle onto the surface of the moon. Minutes later he was joined by Edwin E. Aldrin, Jr. They were the first humans to ...
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