diff --git a/calculator.py b/calculator.py
index 90f5426..37ad91b 100644
--- a/calculator.py
+++ b/calculator.py
@@ -1,31 +1,36 @@
 def add(a, b):
-    pass
+    return a+b
 
 
 def subtract(a, b):
-	pass
-
+    return a-b
 
 def multiply(a, b):
-    pass
+    return a*b
 
 
 def divide(a, b):
-    pass
+    if b==0:
+        return "error"
+    return a/b
 
 
 def pow(a, b):
-    pass
+    return a**b
 
 
 def abs(a):
-    pass
-
+    return a if a>=0 else -a
 
 def mod(a, b):
-    pass
-
+    return a%b
 
 if __name__ == "__main__":
     # 간단한 테스트 코드
-    pass
\ No newline at end of file
+    print("Addition:", add(5, 3))        # 8
+    print("Subtraction:", subtract(5, 3))  # 2
+    print("Multiplication:", multiply(5, 3))  # 15
+    print("Division:", divide(5, 0))      # Error: Division by zero
+    print("Power:", pow(5, 3))            # 125
+    print("Absolute:", abs(-5))           # 5
+    print("Modulus:", mod(5, 3))          #2
\ No newline at end of file