九年级英语全册《unit 9 when was it invented-fascinating facts about the invention》文章素材 人教新目标版

Unit 9 When was it invented-Fascinating facts about the invention文章素材Calculation was a need from the early days when it was necessary to account to others for individual or group actions, particularly in relation to maintaining inventories (of flocks of sheep) or reconciling finances. Early man counted by means of matching one set of objects with another set (stones and sheep). The operations of addition and subtraction were simply the operations of adding or subtracting groups of objects to the sack of counting stones or pebbles. Early counting tables, named abaci, not only formalized this counting method but also introduced the concept of positional notation that we use today. The next logical step was to produce the first "personal calculator"the abacuswhich used the same concepts of one set of objects standing in for objects in another set, but also the concept of a single object standing for a collection of objectspositional notation. The Chinese abacus was developed about 5000 years ago. It was built out of wood and beads. It could be held and carried around easily. The abacus was so successful that its use spread form China to many other countries. The abacus is still in use in some countries today.The abacus does not actually do the computing, as today's calculators do. It helps people keep track of numbers as they do the computing. People who are good at using an abacus can often do calculations as quickly as a person who is using a calculatorThis one-for-one correspondence continued for many centuries even up through the many years when early calculators used the placement of holes in a dial to signify a countsuch as in a rotary dial telephone. Although these machine often had the number symbol engraved alongside the dial holes, the user did not have to know the relationship between the symbols and their numeric value.Primitive people also needed a way to calculate and store information for future use. To keep track of the number of animals killed, they collected small rocks and pebbles in a pile. Each stone stood for one animal. Later they scratched notches and symbols in stone or wood to record and store information. Only when the process of counting and arithmetic became a more abstract process and different sizes of groups were given a symbolic representation so that the results could be written on a "storage medium" such as papyrus or clay did the process of calculation become a process of symbol manipulation. AT A GLANCE: Invention: abacus in c3000 BCabacus / noun . Function: A counting device: a mechanical device for making calculations consisting of a frame mounted with rods along which beads or balls are moved Nationality: Chinese Milestones:3000 BC - The abacus, built out of wood and beads, used the concepts of one set of objects standing in for objects in another set, but also the concept of a single object standing for a collection of objectspositional notation. - Early tables, named abaci, formalized counting and introduced the concept of positional notation.- Early man counted by means of matching one set of objects with another set (stones and sheep).invention, history, inventor of, history of, who invented, invention of, fascinating facts.