Table of Contents
Why is 4 not a happy number?
10-happy numbers 4 → 16 → 37 → 58 → 89 → 145 → 42 → 20 → 4 → , all numbers either lead to 1 and are happy, or lead to the cycle and are unhappy. Because base 10 has no other perfect digital invariants except for 1, no positive integer other than 1 is the sum of the squares of its own digits.
Is 5555 a happy number?
Also you get numbers that add up to other happy numbers e.g. 5555 – four fives squared = 100. These are fixed points so they are happy numbers and any numbers which start sequences ending like this are happy numbers.
What is not a happy number?
never reaches the number 1. The first few unhappy numbers are 2, 3, 4, 5, 6, 8, 9, 11, 12, 14, 15, 16, 17, 18, 20, (OEIS A031177).
What is happy and sad numbers?
A number (positive integer) is called a happy number when it is replaced by the sum of the squares of its digits on a repeated basis until the sum of the squares of its digits equals to 1. On the other hand, numbers that don’t end in 1 are called unhappy or sad numbers.
What is a sad number?
The numbers for which the process of summing up of the squares of its digits ends in 1 are happy numbers. On the other hand, numbers that don’t end in 1 are called unhappy or sad numbers. Here, the number 36 loops endlessly in a cycle which doesn’t end in 1. Therefore 36 is an unhappy or sad number.
How do I know if my number is not happy?
To find whether a given number is happy or not, calculate the square of each digit present in number and add it to a variable sum. If resulting sum is equal to 1 then, given number is a happy number. If the sum is equal to 4 then, the number is an unhappy number.
What is Spy number?
A spy number is a number where the sum of its digits equals the product of its digits. For example, 1124 is a spy number, the sum of its digits is 1+1+2+4=8 and the product of its digits is 1*1*2*4=8.