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A narcissistic number is an n-digit number equal to the sum of each of its digits raised to the nth power. Here's an example: \(153=1^{3}+5^{3}+3^{3} .\) Determine which real numbers are narcissistic. 370

Short Answer

Expert verified
The real number 370 is a narcissistic number.

Step by step solution

01

Splitting the number into its digits

Split the number 370 into three separate digits: 3, 7, and 0.
02

Raising each digit to the third power

Raise each of these digits to the power of 3, which is the number of digits in the original number. This results in the numbers \(3^{3}\) = 27, \(7^{3}\) = 343, and \(0^{3}\) = 0.
03

Asserting the narcissistic condition

Sum these numbers and check if they equal the original number. \(27 + 343 + 0 = 370\), which is indeed the original number, demonstrating that 370 is indeed a narcissistic number.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Mathematical Concepts
In understanding mathematical concepts, one can explore various fascinating properties of numbers, such as those exhibited by narcissistic numbers. These unique numbers are self-referential in nature, in that they are related to the sum of their own digits when each digit is raised to the power of the number of digits the number has.

For a number to be considered narcissistic, the following condition must be met: the sum of its digits raised to the power of the number of digits must equal the original number. For example, the number 153 is a 3-digit number and satisfies the narcissistic condition because \(1^3 + 5^3 + 3^3 = 153\). As educational content creators, we strive to make such interesting mathematical properties both accessible and engaging to students.
Exponentiation
Exponentiation is a form of mathematical operation involving two numbers, the base and the exponent. When a number is raised to the power of another, the base is multiplied by itself as many times as specified by the exponent. For example, \(3^3\) indicates that 3 is to be multiplied by itself twice more (since the first instance is already accounted for), resulting in 27.

In the context of narcissistic numbers, each digit of the number is raised to the power equal to the number of digits in the entire number. Through the process of exponentiation, we can then sum these values to verify the narcissistic quality of the original number.
Digital Root
A digital root is the recursive sum of all the digits in a number until a single-digit number is achieved. This single-digit result, which can be found by summing the digits repeatedly, has properties that are used in number theory and modular arithmetic. For example, the digital root of 370 is found by adding the digits \(3+7+0=10\), and then adding the digits of the result \(1+0=1\).

The digital root, while not directly used to identify narcissistic numbers, is another intriguing property that helps to understand the behavior of numbers under various mathematical operations. It's also related to the concept known as 'casting out nines' used in arithmetic for verification of calculations.
Number Theory
Number theory is a branch of pure mathematics devoted primarily to the study of the integers and integer-valued functions. Within number theory, concepts like prime numbers, divisibility, and the aforementioned narcissistic numbers are studied. Numbers such as 370 are special in number theory because they offer insight into distinctive numerical patterns and properties.

Discovering and verifying narcissistic numbers is an exercise that employs basic number theory concepts as well as pattern recognition. Educators can leverage these unique numbers to spark curiosity and introduce learners to the rich conceptual landscape of number theory.

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Most popular questions from this chapter

The sum, \(S_{n}\), of the first n terms of an arithmetic sequence is given by $$ S_{n}=\frac{n}{2}\left(a_{1}+a_{n}\right), $$ in which \(a_{1}\) is the first term and \(a_{n}\) is the nth term. The sum, \(S_{n}\), of the first \(n\) terms of a geometric sequence is given by $$ S_{n}=\frac{a_{1}\left(1-r^{n}\right)}{1-r}, $$ in which \(a_{1}\) is the first term and \(r\) is the common ratio \((r \neq 1)\). Determine whether each sequence is arithmetic or geometric. Then use the appropriate formula to find \(S_{10}\), the sum of the first ten terms. \(3,-6,12,-24, \ldots\)

Write the first six terms of the geometric sequence with the first term, \(a_{1}\), and common ratio, \(r\). \(a_{1}=-6, r=-5\)

You will develop geometric sequences that model the population growth for California and Texas, the two most populated U.S. states. The table shows the population of Texas for 2000 and 2010 , with estimates given by the U.S. Census Bureau for 2001 through \(2009 .\) $$ \begin{array}{|l|l|l|l|l|l|l|} \hline \text { Year } & \mathbf{2 0 0 0} & \mathbf{2 0 0 1} & \mathbf{2 0 0 2} & \mathbf{2 0 0 3} & \mathbf{2 0 0 4} & \mathbf{2 0 0 5} \\ \hline \begin{array}{l} \text { Population } \\ \text { in millions } \end{array} & 20.85 & 21.27 & 21.70 & 22.13 & 22.57 & 23.02 \\ \hline \end{array} $$ $$ \begin{array}{|l|c|c|c|c|c|} \hline \text { Year } & \mathbf{2 0 0 6} & \mathbf{2 0 0 7} & \mathbf{2 0 0 8} & \mathbf{2 0 0 9} & \mathbf{2 0 1 0} \\ \hline \begin{array}{l} \text { Population } \\ \text { in millions } \end{array} & 23.48 & 23.95 & 24.43 & 24.92 & 25.15 \\ \hline \end{array} $$ a. Divide the population for each year by the population in the preceding year. Round to two decimal places and show that Texas has a population increase that is approximately geometric. b. Write the general term of the geometric sequence modeling Texas's population, in millions, \(n\) years after \(1999 .\) c. Use your model from part (b) to project Texas's population, in millions, for the year 2020 . Round to two decimal places.

Find the indicated term for the geometric sequence with first term, \(a_{1}\), and common ratio, \(r\). Find \(a_{200}\), when \(a_{1}=60, r=1\).

Find the indicated term for the geometric sequence with first term, \(a_{1}\), and common ratio, \(r\). Find \(a_{30}\), when \(a_{1}=8000, r=-\frac{1}{2}\).

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