diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e5cae47
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+# IntelliJ IDEA
+.idea/
+*.iml
+
+# Compiled output
+out/
diff --git a/CodingTest/README.md b/CodingTest/README.md
new file mode 100644
index 0000000..58affa8
--- /dev/null
+++ b/CodingTest/README.md
@@ -0,0 +1,16 @@
+# 🧩 CodingTest
+취업을 위한 코딩테스트 준비
+
+## 👤 이름
+
+- 김환희
+
+## 📌 사용 언어
+
+- Java
+
+## 📋 풀이 목록
+
+| 문제 | 난이도 | 풀이 |
+|------|--------|------|
+| 자릿수 더하기 | Lv.1 | [SumOfDigits.java](../Solutions/SumOfDigits.java) |
diff --git a/README.md b/README.md
index 74a10fa..985899e 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,19 @@
-# CodingTest
+# 🧩 CodingTest
 취업을 위한 코딩테스트 준비
+
+## 👤 이름
+
+- 김환희
+
+## 📌 사용 언어
+
+- Java
+
+## 📋 풀이 목록
+
+| 문제 | 난이도 | 풀이 |
+|------|--------|------|
+| 자릿수 더하기 | Lv.1 | [SumOfDigits.java](Solutions/SumOfDigits.java) |
+| 두 정수 사이의 합 | Lv.1 | [SumofTwoIntegers.java](Solutions/SumofTwoIntegers.java) |
+| 핸드폰 번호 가리기 | Lv.1 | [CoverTheNumber.java](Solutions/CoverTheNumber.java) |
+
diff --git a/Solutions/CoverTheNumber.java b/Solutions/CoverTheNumber.java
new file mode 100644
index 0000000..2ef94fc
--- /dev/null
+++ b/Solutions/CoverTheNumber.java
@@ -0,0 +1,24 @@
+import java.util.*;
+
+
+public class CoverTheNumber {
+
+
+    public static String solution(String phone_number) {
+        char answer[] = phone_number.toCharArray();
+        StringBuilder sb = new StringBuilder();
+
+        int endIndex = answer.length - 4;
+
+        for (int i = 0; i <endIndex; i++) {
+            answer[i] = '*';
+        }
+
+        for (char ch : answer) {
+            sb.append(ch);
+        }
+
+        return sb.toString();
+    }
+
+}
diff --git a/Solutions/Main.java b/Solutions/Main.java
new file mode 100644
index 0000000..65d964b
--- /dev/null
+++ b/Solutions/Main.java
@@ -0,0 +1,11 @@
+import java.util.*;
+
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        String number = sc.nextLine();
+        sc.close();
+        System.out.println(CoverTheNumber.solution(number));
+    }
+}
\ No newline at end of file
diff --git a/Solutions/SumOfDigits.java b/Solutions/SumOfDigits.java
new file mode 100644
index 0000000..b996421
--- /dev/null
+++ b/Solutions/SumOfDigits.java
@@ -0,0 +1,16 @@
+import java.util.*;
+
+public class SumOfDigits {
+
+
+    public static int SumOfDigits(int n) {
+        int answer = 0;
+        String str = String.valueOf(n);
+
+        for (int i = 0; i < str.length(); i++) {
+            answer += str.charAt(i) - '0';
+        }
+
+        return answer;
+    }
+}
diff --git a/Solutions/SumofTwoIntegers.java b/Solutions/SumofTwoIntegers.java
new file mode 100644
index 0000000..981a6d2
--- /dev/null
+++ b/Solutions/SumofTwoIntegers.java
@@ -0,0 +1,32 @@
+import java.util.*;
+
+public class SumofTwoIntegers {
+
+
+    public static long SumofTwoIntegers(int a, int b) {
+        long answer = 0;
+
+        if (a == b) {
+            return a;
+        } else if (a < b) {
+            for (int i = a; i!=b; i++) {
+                answer += i;
+            }
+            return answer + b;
+        } else {
+            for (int i = b; i!=a; i++) {
+                answer += i;
+            }
+            return answer + a;
+        }
+    }
+
+    /**
+     * 피드백: 등차수열의 합 공식을 이용했다면 더 짧게, 높은 성능의 코드가 가능해짐
+     */
+//    public long solution(int a, int b) {
+//        long min = Math.min(a, b);
+//        long max = Math.max(a, b);
+//        return (max - min + 1) * (min + max) / 2;
+//    }
+}