diff --git a/app/src/main/java/com/coderabbit/app/calculator/Calculator.kt b/app/src/main/java/com/coderabbit/app/calculator/Calculator.kt
index 9721a15..19340bf 100644
--- a/app/src/main/java/com/coderabbit/app/calculator/Calculator.kt
+++ b/app/src/main/java/com/coderabbit/app/calculator/Calculator.kt
@@ -9,4 +9,8 @@ class Calculator {
     fun divide(a: Int, b: Int): Int {
         return a/b
     }
+
+    fun minus(a: Int, b: Int): Int {
+        return a - b
+    }
 }
\ No newline at end of file
diff --git a/app/src/test/java/com/coderabbit/app/calculator/CalculatorTest.kt b/app/src/test/java/com/coderabbit/app/calculator/CalculatorTest.kt
index a3a7a19..520b53a 100644
--- a/app/src/test/java/com/coderabbit/app/calculator/CalculatorTest.kt
+++ b/app/src/test/java/com/coderabbit/app/calculator/CalculatorTest.kt
@@ -87,4 +87,10 @@ class CalculatorTest {
             calculator.divide(20,0)
         }
     }
+
+    @Test
+    fun `test minus function be correct`() {
+        val calculator = Calculator()
+        assertEquals(calculator.minus(4,2) ,2)
+    }
 }
\ No newline at end of file