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mathematics

Telephone number

Telephone number is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Telephone number rather than just read about it. In short: A telephone number is the address of a telecommunication endpoint, such as a telephone, in a telephone network, such as the public switched telephone network (PSTN). A telephone number typically consists of a sequence of digits, but historically letters were also used in connection with telephone exchange names.

Telephone number — main illustration
Telephone number — illustration

Key takeaways

  • Telephone number belongs to mathematics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Telephone number to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Telephone number from memory before moving on to harder problems.

Reference excerpt

A telephone number is the address of a telecommunication endpoint, such as a telephone, in a telephone network, such as the public switched telephone network (PSTN). A telephone number typically consists of a sequence of digits, but historically letters were also used in connection with telephone exchange names. Telephone numbers facilitate the switching and routing of calls using a system of destination code routing. Telephone numbers are entered or dialed by a calling party on the originating telephone set, which transmits the sequence of digits in the process of signaling to a telephone exchange. The exchange completes the call either to another locally connected subscriber or via the PSTN to the called party. Telephone numbers are assigned within the framework of a national or regional telephone numbering plan to subscribers by telephone service operators, which may be commercial entities, state-controlled administrations, or other telecommunication industry associations. Telephone numbers were first used in 1879 in Lowell, Massachusetts, when they replaced the request for subscriber names by callers connecting to the switchboard operator. Over the course of telephone history, telephone numbers had various lengths and formats and even included most letters of the alphabet in leading positions when telephone exchange names were in common use until the 1960s. Telephone numbers are often dialed in conjunction with other signaling code sequences, such as vertical service codes, to invoke special telephone service features. Telephone numbers may have associated short dialing codes, such as 9-1-1, which obviate the need to remember and dial complete telephone numbers.

Concept and methodology

… excerpt ends here. Continue reading the full article.

Illustrations

Telephone number: A Swiss rotary telephone dial from the 1970s showing the telephone's number (94 29 68), along with those of various local emergency services
A Swiss rotary telephone dial from the 1970s showing the telephone's number (94 29 68), along with those of various local emergency services
Telephone number: Telephone numbers for sale in Hong Kong
Telephone numbers for sale in Hong Kong
Telephone number: A business card from Richard Nixon's first Congressional campaign in 1946. His telephone number can be seen as "Whittier 42635".
A business card from Richard Nixon's first Congressional campaign in 1946. His telephone number can be seen as "Whittier 42635".
Telephone number: Face of a 1939 rotary dial showing a 2L-4N style alphanumeric telephone number LA-2697
Face of a 1939 rotary dial showing a 2L-4N style alphanumeric telephone number LA-2697
Telephone number: 2008 photo shows a hairdressing shop in Toronto with an exterior sign showing the shop's telephone number in the old two-letters plus five-digits format.
2008 photo shows a hairdressing shop in Toronto with an exterior sign showing the shop's telephone number in the old two-letters plus five-digits format.

Worked examples

Example 1 — a first encounter with Telephone number

Start with the simplest possible case. Write down what Telephone number claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Telephone number before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Telephone number ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Telephone number

In research
Telephone number appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Telephone number in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Telephone number is common in secondary-school and first-year university syllabi. It links to neighbouring topics Identifiers, Network addressing, Telephone numbers, so understanding it makes those chapters shorter.
In everyday life
Look for Telephone number outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Telephone number in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Telephone number means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Telephone number out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Telephone number in simple terms?

A telephone number is the address of a telecommunication endpoint, such as a telephone, in a telephone network, such as the public switched telephone network (PSTN). A telephone number typically consists of a sequence of digits, but historically letters were also used in connection with telephone e…

Why does Telephone number matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Telephone number?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Telephone number.

Tags

  • Identifiers
  • Network addressing
  • Telephone numbers

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