A neon number is a number where the sum of the digits of its square equals the number itself. For example, the square of 9 is 81, and the sum of its digits (8 + 1) equals 9, making it a neon number. Conversely, the square of 6 is 36, but the sum of its digits (3 + 6) equals 9, which is not equal to 6, so 6 is not a neon number. The algorithm involves squaring the number, summing the digits of the square using a loop, and checking if the sum matches the original number.
This video explores three approaches to check neon numbers: using a while loop, a recursive method, and a string function with a for loop. These methods illustrate different ways to implement the algorithm effectively in C.
For more details, please go through - C Program To Check Neon Number