### Problem Statement

We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself.Link to GitHub :Code

Example:

Input: n = 15 Output: false Divisors of 15 are 1, 3 and 5. Sum of divisors is 9 which is not equal to 15. Input: n = 6 Output: true Divisors of 6 are 1, 2 and 3. Sum of divisors is 6.

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**Solution**

**A Simple Solution**is to go through every number from 1 to n-1 and check if it is a divisor. Maintain sum of all divisors. If sum becomes equal to n, then return true, else return false.

**An Efficient Solution**is to go through numbers till square root of n. If a number ‘i’ divides n, then add both ‘i’ and n/i to sum.

public class PerfectNumber { public static boolean get(int num) { //If num is 1 then return false if (num==1) return false; int sum=0; for(int i=2;i<=Math.sqrt(num);i++) { if(num%i==0){sum+=i;} if(i!=num/i) sum+=num/i; } sum++; return sum == num; } }

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