diff --git a/.idea/gradle.xml b/.idea/gradle.xml
new file mode 100644
index 0000000..ce1c62c
--- /dev/null
+++ b/.idea/gradle.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GradleMigrationSettings" migrationVersion="1" />
+  <component name="GradleSettings">
+    <option name="linkedExternalProjectsSettings">
+      <GradleProjectSettings>
+        <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="modules">
+          <set>
+            <option value="$PROJECT_DIR$" />
+          </set>
+        </option>
+      </GradleProjectSettings>
+    </option>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..25d34a4
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" project-jdk-name="11" project-jdk-type="JavaSDK" />
+</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..35eb1dd
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/main/java/calculator/Application.java b/src/main/java/calculator/Application.java
index d909a50..893fa5a 100644
--- a/src/main/java/calculator/Application.java
+++ b/src/main/java/calculator/Application.java
@@ -7,5 +7,6 @@ public static void main(String[] args) {
         // 예시 코드
         Calculator calculator = new Calculator();
         calculator.calculate("");
+
     }
 }
diff --git a/src/main/java/calculator/Calculator.java b/src/main/java/calculator/Calculator.java
index 88e8552..92dc6f7 100644
--- a/src/main/java/calculator/Calculator.java
+++ b/src/main/java/calculator/Calculator.java
@@ -1,13 +1,38 @@
 package calculator;
-
-/*
-    1주차에만 제공되는 예시 코드입니다.
-    코드는 그대로 사용해도 되고 수정해도 됩니다.
- */
+import java.util.Objects;
 
 public class Calculator {
     public int calculate(String input) {
         // TODO: 코드 구현
-        throw new IllegalArgumentException("아직 구현되지 않았습니다.");
+        if(input.isEmpty()){
+            return 0;
+        }
+        int result=0;
+        int num=0;
+        char b='+';
+        for(int i=0;i<input.length();i++){
+            char a=input.charAt(i);
+            boolean isNum = Character.isDigit(a);
+
+            if(isNum){
+                num=a-'0';
+                switch(b){
+                    case '+': result+=num; break;
+                    case '-': result-=num; break;
+                    case '*': result*=num; break;
+                    case '/':
+                        if(num==0){
+                            throw new IllegalArgumentException("0 입력 불가능");
+                        }
+                        result/=num; break;
+                }
+            }
+            else if(a=='+' || a=='-' || a=='*' || a=='/'){
+                b=a;
+            }
+                throw new IllegalArgumentException("잘못된 수식 입력");
+        }
+
+        return result;
     }
 }