diff --git a/src/main/java/org/example/solution1.java b/src/main/java/org/example/solution1.java
index cadc0ab..b71a569 100644
--- a/src/main/java/org/example/solution1.java
+++ b/src/main/java/org/example/solution1.java
@@ -1,15 +1,14 @@
 package org.example;
 
-public class solution1 {
-    public double solution(int[] arr) {
-        double answer = 0;
-        double tot =0;
-        for(int i: arr){
-            tot += i;
+class solution1 {
+    public String solution(int num) {
+        String answer = "";
+        if(num % 2 == 0){
+            answer += "Even";
+        }else {
+            answer += "Odd";
         }
-        answer = tot/(arr.length);
         return answer;
-        //커밋연습
     }
 }
 
diff --git a/src/main/java/org/example/solution2.java b/src/main/java/org/example/solution2.java
new file mode 100644
index 0000000..77541e0
--- /dev/null
+++ b/src/main/java/org/example/solution2.java
@@ -0,0 +1,12 @@
+package org.example;
+
+class solution2 {
+    public double solution(int[] arr) {
+        double answer = 0;
+        for(int i = 0; i<arr.length; i++){
+            answer = answer + (double)arr[i];
+        }
+        answer = answer/(double)arr.length;
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution3.java b/src/main/java/org/example/solution3.java
new file mode 100644
index 0000000..f284261
--- /dev/null
+++ b/src/main/java/org/example/solution3.java
@@ -0,0 +1,13 @@
+package org.example;
+
+public class solution3 {
+    public int solution(int n) {
+        int answer = 0;
+        String str = Integer.toString(n);
+        for(char x : str.toCharArray()){
+            int a = x - 48;
+            answer = answer + a;
+        }
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution4.java b/src/main/java/org/example/solution4.java
new file mode 100644
index 0000000..55224b0
--- /dev/null
+++ b/src/main/java/org/example/solution4.java
@@ -0,0 +1,20 @@
+package org.example;
+
+public class solution4 {
+    boolean solution(String s) {
+        boolean answer = true;
+        int p = 0;
+        int y = 0;
+        for (int i = 0; i < s.length(); i++) {
+            if (s.charAt(i) == 'p' || s.charAt(i) == 'P') {
+                p++;
+            } else if (s.charAt(i) == 'y' || s.charAt(i) == 'Y') {
+                y++;
+            }
+        }
+        if (p != y) {
+            answer = false;
+        }
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution5.java b/src/main/java/org/example/solution5.java
new file mode 100644
index 0000000..f65137c
--- /dev/null
+++ b/src/main/java/org/example/solution5.java
@@ -0,0 +1,14 @@
+package org.example;
+
+public class solution5 {
+    public int solution(int n) {
+        int answer = 0;
+        for(int i = 1; i<n; i++){
+            if(n%i == 1){
+                answer = i;
+                break;
+            }
+        }
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution6.java b/src/main/java/org/example/solution6.java
new file mode 100644
index 0000000..da093e9
--- /dev/null
+++ b/src/main/java/org/example/solution6.java
@@ -0,0 +1,18 @@
+package org.example;
+
+public class solution6 {
+    public boolean solution(String s) {
+        boolean answer = true;
+        char [] arr = s.toCharArray();
+
+        if(arr.length!=4 && arr.length!=6){
+            return false;
+        }
+        for(int i = 0; i<arr.length; i++){
+            if(arr[i]<'0' || arr[i]>'9'){
+                return false;
+            }
+        }
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution7.java b/src/main/java/org/example/solution7.java
new file mode 100644
index 0000000..51f737f
--- /dev/null
+++ b/src/main/java/org/example/solution7.java
@@ -0,0 +1,10 @@
+package org.example;
+
+public class solution7 {
+    public boolean solution(int x) {
+        boolean answer = false;
+        int y = x/10000 + x%10000/1000 + x%10000%1000/100 + x%10000%1000%100/10 +x%10000%1000%100%10/1;
+        if(x%y==0) answer = true;
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution8.java b/src/main/java/org/example/solution8.java
new file mode 100644
index 0000000..aaae6b1
--- /dev/null
+++ b/src/main/java/org/example/solution8.java
@@ -0,0 +1,21 @@
+package org.example;
+
+import java.util.*;
+
+class solution8 {
+    public String solution(String[] seoul) {
+        String answer = "";
+        StringBuilder sb = new StringBuilder();
+        int x = 0;
+        for(int i = 0; i<seoul.length; i++){
+            if("Kim".equals(seoul[i])){
+                x = i;
+            }
+        }
+        sb.append("김서방은 ");
+        sb.append(Integer.toString(x));
+        sb.append("에 있다");
+        answer = sb.toString();
+        return answer;
+    }
+}
diff --git a/src/main/java/org/example/solution9.java b/src/main/java/org/example/solution9.java
new file mode 100644
index 0000000..fdd472d
--- /dev/null
+++ b/src/main/java/org/example/solution9.java
@@ -0,0 +1,17 @@
+package org.example;
+
+public class solution9 {
+    //매개변수의 자료형이 int이면 오버플로우 발생으로 자료형을 long으로 바꿔줘야함
+    public int solution(long num) {
+        int answer = 0;
+        while(num != 1){
+            answer++;
+            if(answer==500){
+                answer = -1;
+                break;
+            }
+            num = num % 2 == 0 ? num / 2 : num * 3 + 1;
+        }
+        return answer;
+    }
+}