I made a simple calculation problem game in Java

Addition game

Suddenly, I remembered a game called DS training for adults who train their brains. Training on how to quickly solve the addition recorded in the game I wanted to play, so I wrote the program myself. Below is the code.

Main.java

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Random;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int count = 0;
		long start = 0;
		long stop = 0;
		long timeresult = 0;
		Scanner sc = new Scanner(System.in);
		System.out.println("I will give you a calculation problem.");
		System.out.println("You will be asked 10 questions.");
		System.out.println("Start with Enter.");
		String anykey = sc.nextLine();
		System.out.println("------------------------------");

		for(int i = 0; i < 10; i++) {
			start = System.nanoTime();
			Random rnd = new Random();
			int figure1 = rnd.nextInt(30) + 1;
			int figure2 = rnd.nextInt(30) + 1;
			int result = figure1 + figure2;
			System.out.println(figure1 + " + " + figure2 + " = ?");
			int a = sc.nextInt();
			if(result == a) {
				System.out.println("Is the correct answer.");
				count++;
			} else {
				System.out.println("It's an incorrect answer.");
			}
		}
		stop = System.nanoTime();
		System.out.println("------------------------------");
		timeresult = stop - start;
		double timesecond = timeresult / 100000000.0;
		BigDecimal bdt = new BigDecimal(String.valueOf(timesecond));
		BigDecimal bdt1 = bdt.setScale(2, RoundingMode.HALF_UP);
		System.out.println("The number of correct answers is" + count + "It was a question.");
		System.out.println("The time it took to solve" + bdt1 + "It was seconds.");
	}
}

In this game, 10 questions are added in a row, and the player solves them. When the game is over, the number of correct answers and the clearing time will be displayed. I found out by actually playing it, but if you try to solve it quickly I make a calculation error. Also, in the DS brain training, I wrote the answer with a touch pen, but here is Because it is input with the keyboard, it is necessary to get used to inputting numbers quickly and continuously thought. It's a very simple game, but it's a lot of fun.

What i learned

I learned about the existence of a method called nanoTime. I feel that it is very versatile, and at the same time, it is suitable for programs of various genres. I thought it could be used.

If you want to add more

In the DS brain training, evaluations such as "walking class" and "Shinkansen class" are given depending on the training results. I remember it well. Even in this program, even if there is such an expression as a comprehensive evaluation of the number of correct answers and clearing time I thought it was interesting.