3rd October 2019

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# What are the Armstrong numbers?

An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since 3**3 + 7**3 + 1**3 = 371. Write a program to find all Armstrong number in the range of 0 and 999.

Subsequently, one may also ask, what is the perfect number?

In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum).

What is a happy number?

Happy number. A happy number is defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits in base-ten, and repeat the process until the number either equals 1 (where it will stay), or it loops endlessly in a cycle that does not include 1.

What is meant by Adam Number?

Adam Number. Adam number is a number when reversed, the square of the number and the square of the reversed number should be numbers which are reverse of each other. Adam numbers upto 1000 are: 0, 1, 2, 3, 11, 12, 13, 21, 22, 31, 101, 102, 103, 111, 112 , 113, 121, 122, 201, 202, 211, 212, 221, 301, 311.