diff --git a/build/test/cache/test_mod.c b/build/test/cache/test_mod.c
new file mode 100644
index 0000000..a31e4eb
--- /dev/null
+++ b/build/test/cache/test_mod.c
@@ -0,0 +1,47 @@
+#include "src/main/c/Calculator/calculator.h"
+#include "/var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity.h"
+
+
+
+
+
+
+void setUp(void){
+
+
+
+}
+
+void tearDown(void){
+
+}
+
+
+
+
+
+void test_mod(void){
+
+
+
+    int result;
+
+
+
+
+
+
+
+    result = mod(10, 5);
+
+
+
+
+
+    UnityAssertEqualNumber((UNITY_INT)((0)), (UNITY_INT)((result)), (
+
+   ((void *)0)
+
+   ), (UNITY_UINT)(22), UNITY_DISPLAY_STYLE_INT);
+
+}
diff --git a/build/test/dependencies/test_mod.d b/build/test/dependencies/test_mod.d
new file mode 100644
index 0000000..66da587
--- /dev/null
+++ b/build/test/dependencies/test_mod.d
@@ -0,0 +1,4 @@
+build/test/out/c/test_mod.o: test/Calculator/test_mod.c \
+ /var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity.h \
+ /var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity_internals.h \
+ src/main/c/Calculator/calculator.h
diff --git a/build/test/dependencies/test_mod_runner.d b/build/test/dependencies/test_mod_runner.d
new file mode 100644
index 0000000..2281947
--- /dev/null
+++ b/build/test/dependencies/test_mod_runner.d
@@ -0,0 +1,3 @@
+build/test/out/c/test_mod_runner.o: build/test/runners/test_mod_runner.c \
+ /var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity.h \
+ /var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity_internals.h
diff --git a/build/test/out/c/calculator.o b/build/test/out/c/calculator.o
index b3aa454..dd0432c 100644
Binary files a/build/test/out/c/calculator.o and b/build/test/out/c/calculator.o differ
diff --git a/build/test/out/c/test_mod.o b/build/test/out/c/test_mod.o
new file mode 100644
index 0000000..4eb2448
Binary files /dev/null and b/build/test/out/c/test_mod.o differ
diff --git a/build/test/out/c/test_mod_runner.o b/build/test/out/c/test_mod_runner.o
new file mode 100644
index 0000000..1aec833
Binary files /dev/null and b/build/test/out/c/test_mod_runner.o differ
diff --git a/build/test/out/test_factorial.out b/build/test/out/test_factorial.out
index 839f316..4d75a66 100755
Binary files a/build/test/out/test_factorial.out and b/build/test/out/test_factorial.out differ
diff --git a/build/test/out/test_mod.out b/build/test/out/test_mod.out
new file mode 100755
index 0000000..2e2b3f2
Binary files /dev/null and b/build/test/out/test_mod.out differ
diff --git a/build/test/out/test_pow.out b/build/test/out/test_pow.out
index 5b79e45..e0ea990 100755
Binary files a/build/test/out/test_pow.out and b/build/test/out/test_pow.out differ
diff --git a/build/test/preprocess/files/test_mod.c b/build/test/preprocess/files/test_mod.c
new file mode 100644
index 0000000..a31e4eb
--- /dev/null
+++ b/build/test/preprocess/files/test_mod.c
@@ -0,0 +1,47 @@
+#include "src/main/c/Calculator/calculator.h"
+#include "/var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity.h"
+
+
+
+
+
+
+void setUp(void){
+
+
+
+}
+
+void tearDown(void){
+
+}
+
+
+
+
+
+void test_mod(void){
+
+
+
+    int result;
+
+
+
+
+
+
+
+    result = mod(10, 5);
+
+
+
+
+
+    UnityAssertEqualNumber((UNITY_INT)((0)), (UNITY_INT)((result)), (
+
+   ((void *)0)
+
+   ), (UNITY_UINT)(22), UNITY_DISPLAY_STYLE_INT);
+
+}
diff --git a/build/test/preprocess/includes/test_mod.c b/build/test/preprocess/includes/test_mod.c
new file mode 100644
index 0000000..f2efae7
--- /dev/null
+++ b/build/test/preprocess/includes/test_mod.c
@@ -0,0 +1,3 @@
+---
+- "/var/lib/gems/3.0.0/gems/ceedling-0.31.1/vendor/unity/src/unity.h"
+- src/main/c/Calculator/calculator.h
diff --git a/build/test/results/test_factorial.pass b/build/test/results/test_factorial.pass
index 4f128ef..6e380e2 100644
--- a/build/test/results/test_factorial.pass
+++ b/build/test/results/test_factorial.pass
@@ -15,4 +15,4 @@
   :failed: 0
   :ignored: 0
 :stdout: []
-:time: 0.00677925901254639
+:time: 0.006395165983121842
diff --git a/build/test/results/test_mod.pass b/build/test/results/test_mod.pass
new file mode 100644
index 0000000..26827d7
--- /dev/null
+++ b/build/test/results/test_mod.pass
@@ -0,0 +1,18 @@
+---
+:source:
+  :path: test/Calculator
+  :file: test_mod.c
+:successes:
+- :test: test_mod
+  :line: 13
+  :message: ''
+  :unity_test_time: 0
+:failures: []
+:ignores: []
+:counts:
+  :total: 1
+  :passed: 1
+  :failed: 0
+  :ignored: 0
+:stdout: []
+:time: 0.006040317006409168
diff --git a/build/test/results/test_pow.pass b/build/test/results/test_pow.pass
index 5767cde..23e7f73 100644
--- a/build/test/results/test_pow.pass
+++ b/build/test/results/test_pow.pass
@@ -19,4 +19,4 @@
   :failed: 0
   :ignored: 0
 :stdout: []
-:time: 0.006241032999241725
+:time: 0.005650753009831533
diff --git a/build/test/runners/test_mod_runner.c b/build/test/runners/test_mod_runner.c
new file mode 100644
index 0000000..198a7ca
--- /dev/null
+++ b/build/test/runners/test_mod_runner.c
@@ -0,0 +1,81 @@
+/* AUTOGENERATED FILE. DO NOT EDIT. */
+
+/*=======Automagically Detected Files To Include=====*/
+#include "unity.h"
+
+int GlobalExpectCount;
+int GlobalVerifyOrder;
+char* GlobalOrderError;
+
+/*=======External Functions This Runner Calls=====*/
+extern void setUp(void);
+extern void tearDown(void);
+extern void test_mod(void);
+
+
+/*=======Mock Management=====*/
+static void CMock_Init(void)
+{
+  GlobalExpectCount = 0;
+  GlobalVerifyOrder = 0;
+  GlobalOrderError = NULL;
+}
+static void CMock_Verify(void)
+{
+}
+static void CMock_Destroy(void)
+{
+}
+
+/*=======Test Reset Options=====*/
+void resetTest(void);
+void resetTest(void)
+{
+  tearDown();
+  CMock_Verify();
+  CMock_Destroy();
+  CMock_Init();
+  setUp();
+}
+void verifyTest(void);
+void verifyTest(void)
+{
+  CMock_Verify();
+}
+
+/*=======Test Runner Used To Run Each Test=====*/
+static void run_test(UnityTestFunction func, const char* name, UNITY_LINE_TYPE line_num)
+{
+    Unity.CurrentTestName = name;
+    Unity.CurrentTestLineNumber = line_num;
+#ifdef UNITY_USE_COMMAND_LINE_ARGS
+    if (!UnityTestMatches())
+        return;
+#endif
+    Unity.NumberOfTests++;
+    UNITY_CLR_DETAILS();
+    UNITY_EXEC_TIME_START();
+    CMock_Init();
+    if (TEST_PROTECT())
+    {
+        setUp();
+        func();
+    }
+    if (TEST_PROTECT())
+    {
+        tearDown();
+        CMock_Verify();
+    }
+    CMock_Destroy();
+    UNITY_EXEC_TIME_STOP();
+    UnityConcludeTest();
+}
+
+/*=======MAIN=====*/
+int main(void)
+{
+  UnityBegin("test_mod.c");
+  run_test(test_mod, "test_mod", 13);
+
+  return UnityEnd();
+}
diff --git a/src/main/c/Calculator/calculator.c b/src/main/c/Calculator/calculator.c
index 95d3980..2243f86 100644
--- a/src/main/c/Calculator/calculator.c
+++ b/src/main/c/Calculator/calculator.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <math.h>
 #define M_PI 3.14159265358979323
 
 
@@ -11,6 +12,7 @@ double factorial(double num);
 double permutation(int n, int r);
 double combination(int n, int r);
 double pow(double num1, double num2);
+int    mod(int num1,int num2);
 
     int calculator() {
     int choice;
@@ -85,7 +87,7 @@ double pow(double num1, double num2);
         case 5:
             return pow(num1, num2);
         case 6:
-            return 0;// fmod(num1, num2);
+            return 0; fmod(num1, num2);
         case 7:
             return 0;// log(num1);
         case 8:
@@ -156,3 +158,7 @@ double pow(double num1, double num2){
     }
     return product;
 }
+int mod(int num1, int num2){
+    int result = num1%num2;
+    return result;
+}
diff --git a/src/main/c/Calculator/calculator.h b/src/main/c/Calculator/calculator.h
index 8d0213a..5ca9657 100644
--- a/src/main/c/Calculator/calculator.h
+++ b/src/main/c/Calculator/calculator.h
@@ -4,5 +4,6 @@
 int calculator();
 double pow(double num1, double num2);
 double factorial(double num);
+int mod(int num1, int num2);
 
 #endif
diff --git a/test/Calculator/test_mod.c b/test/Calculator/test_mod.c
new file mode 100644
index 0000000..fde7554
--- /dev/null
+++ b/test/Calculator/test_mod.c
@@ -0,0 +1,26 @@
+#ifdef TEST
+#include "unity.h"
+#include "calculator.h"
+#include "math.h"
+
+void setUp(void){
+    //Wenn Funktion Vorraussetzungen braucht
+}
+void tearDown(void){
+}
+
+
+void test_mod(void){
+    /* arrange */
+    int result;
+  
+
+    /* act */
+    result = mod(10, 5);
+
+    /* assert */
+    TEST_ASSERT_EQUAL_INT(0, result);//10%5
+}
+
+
+#endif // TEST