diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 0000000..2b11309
Binary files /dev/null and b/.DS_Store differ
diff --git a/src/practice01/Prob1.java b/src/practice01/Prob1.java
index c038781..b33a4a0 100644
--- a/src/practice01/Prob1.java
+++ b/src/practice01/Prob1.java
@@ -2,11 +2,20 @@
 
 import java.util.Scanner;
 
+
 public class Prob1 {
+
 	public static void main(String[] args) {
-		Scanner scanner = new Scanner( System.in );
-		
-		
-		scanner.close();
+		// TODO Auto-generated method stub
+
+		Scanner sc=new Scanner(System.in);
+		int num;
+		System.out.print("Please enter a number:");
+		num=sc.nextInt();
+		if(num%3==0)
+			System.out.println("3의 배수입니다.");
+		else
+			System.out.println("3의 배수가 아닙니다.");
 	}
+
 }
diff --git a/src/practice01/Prob2.java b/src/practice01/Prob2.java
index 32d40f0..937d20e 100644
--- a/src/practice01/Prob2.java
+++ b/src/practice01/Prob2.java
@@ -1,6 +1,20 @@
 package practice01;
 
 public class Prob2 {
+
 	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+		for(int i=0;i<10;i++)
+		{
+			for(int j=i;j<i+10;j++)
+			{
+				System.out.print(j+" ");
+			}
+			System.out.println();
+		}
+		
+		
 	}
+
 }
diff --git a/src/practice01/Prob3.java b/src/practice01/Prob3.java
index 3b7ab3c..cf76c28 100644
--- a/src/practice01/Prob3.java
+++ b/src/practice01/Prob3.java
@@ -1,7 +1,31 @@
 package practice01;
 
+import java.util.Scanner;
+
 public class Prob3 {
 	
 	public static void main(String[] args) {
+		Scanner sc=new Scanner(System.in);
+		int num,sum=0;
+		System.out.print("Please enter a number:");
+		num=sc.nextInt();
+		
+		if(num%2==0)
+		{
+			for(int i=2;i<=num;i+=2)
+			{
+				sum+=i;
+			}
+		}
+		else
+		{
+			for(int i=1;i<=num;i+=2)
+			{
+				sum+=i;
+			}
+	
+		}
+		System.out.println("result:"+sum);
+			
 	}
 }
diff --git a/src/practice01/Prob4.java b/src/practice01/Prob4.java
index 7d38c33..014b6f3 100644
--- a/src/practice01/Prob4.java
+++ b/src/practice01/Prob4.java
@@ -1,9 +1,26 @@
 package practice01;
 
+import java.util.Scanner;
 
 public class Prob4 {
 
 	public static void main(String[] args) {
+		Scanner sc=new Scanner(System.in);
+		String str=null;
+		System.out.print("Please enter a String:");
+		str=sc.nextLine();
+		char [] arr=str.toCharArray();
+		
+		for(int i=0;i<str.length();i++)
+		{
+			for(int j=0;j<=i;j++)
+			{
+				System.out.print(arr[j]);
+			}
+			System.out.println();
+		}
+		
+		
 	}
 
 }
diff --git a/src/practice01/Prob5.java b/src/practice01/Prob5.java
index d8d08ad..3979178 100644
--- a/src/practice01/Prob5.java
+++ b/src/practice01/Prob5.java
@@ -3,5 +3,22 @@
 public class Prob5 {
 
 	public static void main(String[] args) {
+
+		boolean check = false;
+		for (int i = 1; i < 100; i++) {
+			StringBuilder str = new StringBuilder();
+			str.append(i + " ");
+			for (int j = 0; j < str.length() - 1; j++) {
+				if (str.charAt(j) == '3' || str.charAt(j) == '6' || str.charAt(j) == '9') {
+					str.append("짝");
+					check = true;
+				}
+			} 
+			if (check) {
+				System.out.println(str);
+				check = false;
+			}
+		}
+
 	}
 }