Enter your approximated PI number, desired precision and find out if you guessed well.

pi-guesser.java

package com.company;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    private static BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
    private static String fullPi = String.valueOf(Math.PI);

    public static void main(String[] args) throws IOException {
        String yourPiGuess = readPi();
        int precision = readPrecision();

        printResult(yourPiGuess, precision);
    }

    private static String readPi() throws IOException {
        System.out.println("Full PI:" + fullPi);
        System.out.println("Enter your PI guess: ");

        return consoleReader.readLine();
    }

    private static int readPrecision() throws IOException {
        System.out.println("Enter your precision: ");

        return Integer.parseInt(consoleReader.readLine());
    }

    private static void printResult(String yourPiGuess, int precision) {
        if (yourPiGuess.length() < precision) {
            return;
        }

        if (fullPi.substring(0, precision).equals(yourPiGuess.substring(0, precision))) {
            System.out.println("You are right");
        } else {
            System.out.println("Wrong");
        }
    }
}