# [Java] I made a simple calculation problem game in Java

Suddenly, I remembered a game called adult DS training that trains the brain Training how to quickly solve the addition that was 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 ask a calculation question.");
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("Yes.");
count++;
} else {
System.out.println("Incorrect.");
}
}
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 correct number was "+ count + "question.");
System.out.println("The time it took to solve was "+ bdt1 + "seconds.");
}
}
``````

In this game, 10 questions in addition are added, and the player solves them. When the game ends, the number of correct answers and the clear time will be displayed. I found out by actually playing it, but when trying to solve it quickly I will make a mistake in the calculation. Also, in the brain training of DS, I wrote the answer with a touch pen, but this is You need to get used to entering numbers in quick succession because you use the keyboard. thought. It’s a very simple game, but quite fun.

# What we 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 things like this

In the brain training of DS, evaluation such as “walking grade” and “Shinkansen grade” depending on the training result I remember it was there. Even in this program, even if there are such expressions as a comprehensive evaluation of the number of correct answers and the clear time I thought it was interesting.

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