46 Interface simple and compound interest

import java.io.*;
interface Interest{
    double p=5000, t=2, r=18;
    double SimpleInterest();
    double CompoundInterest();
}
class Main implements Interest{
    public double SimpleInterest(){
        return (p * t * r)/100;
    }
    public double CompoundInterest(){
        return p * (Math.pow(1+r/100, t) - 1);//principal * (Math.pow((1 + rate/100), (time * number))) - principa
    }
    public static void main (String args[]){
        Main obj = new Main();
        double ci = obj.CompoundInterest();
        double si = obj.SimpleInterest();
        System.out.println("Simple interest is "+si);
        System.out.println("Compound interest is "+ci);
    }
}
/*
Simple interest is 1800.0
Compound interest is 1961.9999999999993
*/