diff --git a/src/main/c/BasicMode.c b/src/main/c/BasicMode.c
index 9904742..396440f 100644
--- a/src/main/c/BasicMode.c
+++ b/src/main/c/BasicMode.c
@@ -1,8 +1,56 @@
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-#include <math.h>
-
-#include "taschenrechner.h"
-
-
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "taschenrechner.h"
+
+
+void BasicMode() {
+	char endtmp = '0';	//0 false, 1 true
+	double result = 0;
+	double numbers[100] = {0.0};
+	char operatoren[100];
+
+	do {
+		//100 doubles in this array  goes through the for loop till 100 numbers or = is entered
+		for (int i = 0; i < 100) {
+			printf("Enter a Number: ");
+			numbers[i] = testForNumber();	//gets number
+
+			printf("Enter a operation: ");
+			operator[i] = testForOperator();	//gets operator
+
+			if (i > 1) {	//if function to prevent numbers[-1] 
+				switch (operator[i])		//checks of the operator and switches to the case with the needed function
+				{
+				case '+': 
+					result += add(numbers[i - 1], numbers[i])
+					break;
+
+				case '-':
+					result += minus(numbers[i - 1], numbers[i])
+					break;
+
+				case '*':
+					result += multiply(numbers[i - 1], numbers[i])
+					break;
+
+				case '/':
+					result += divide(numbers[i - 1], numbers[i])
+					break;
+
+				case '=':
+					printf("The result is: %d", result);
+					endtmp = 1;
+					break;
+
+				default:
+					break;
+				}
+			}
+			i++;
+		}
+	} while (endtmp != '1')
+
+}
diff --git a/src/main/c/taschenrechner.h b/src/main/c/taschenrechner.h
index 23cc26f..3855a6c 100644
--- a/src/main/c/taschenrechner.h
+++ b/src/main/c/taschenrechner.h
@@ -1,56 +1,59 @@
-#ifndef TASCHENRECHNER_H
-#define TASCHENRECHNER_H
-
-//add function
-doulbe add(doulbe a, doulbe b);
-
-//minus function
-doulbe minus(doulbe a, doulbe b);
-
-//multiply function
-doulbe multiply(doulbe a, doulbe b);
-
-//divide function
-doulbe divide(doulbe a, doulbe b);
-
-//get input and check if its a number
-double testForNumber()
-
-// Square root function
-double squareRootFunction(double x);
-
-//..
-// Trigonometric functions
-double sineFunction(double angle);
-
-double cosineFunction(double angle);
-
-double tangentFunction(double angle);
-
-//..
-// Logarithmic functions
-double logarithmFunction(double x);
-
-double naturalLogarithmFunction(double x);
-
-double logarithmBase2Function(double x);
-
-//..
-// Exponential function
-double exponentialFunction(double x);
-
-// ..
-// Bitwise AND function
-int bitwiseAND(int num1, int num2);
-
-// Bitwise OR function
-int bitwiseOR(int num1, int num2);
-
-// Bitwise XOR function
-int bitwiseXOR(int num1, int num2);
-
-int mode(int userChoice);
-
-int displayMenu();
-
-#endif // TASCHENRECHNER_H
+#ifndef TASCHENRECHNER_H
+#define TASCHENRECHNER_H
+
+//add function
+doulbe add(doulbe a, doulbe b);
+
+//minus function
+doulbe minus(doulbe a, doulbe b);
+
+//multiply function
+doulbe multiply(doulbe a, doulbe b);
+
+//divide function
+doulbe divide(doulbe a, doulbe b);
+
+//get input and check if its a number
+double testForNumber()
+
+//get input and check if its a operator
+char testForOperator()
+
+// Square root function
+double squareRootFunction(double x);
+
+//..
+// Trigonometric functions
+double sineFunction(double angle);
+
+double cosineFunction(double angle);
+
+double tangentFunction(double angle);
+
+//..
+// Logarithmic functions
+double logarithmFunction(double x);
+
+double naturalLogarithmFunction(double x);
+
+double logarithmBase2Function(double x);
+
+//..
+// Exponential function
+double exponentialFunction(double x);
+
+// ..
+// Bitwise AND function
+int bitwiseAND(int num1, int num2);
+
+// Bitwise OR function
+int bitwiseOR(int num1, int num2);
+
+// Bitwise XOR function
+int bitwiseXOR(int num1, int num2);
+
+int mode(int userChoice);
+
+int displayMenu();
+
+#endif // TASCHENRECHNER_H
diff --git a/src/main/c/testForOperator.c b/src/main/c/testForOperator.c
new file mode 100644
index 0000000..51b1931
--- /dev/null
+++ b/src/main/c/testForOperator.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "taschenrechner.h"
+
+char testForOperator() {
+    //saving the number of operators in a variable so it only needs to be changed in one location
+    int numberOfOperators = 5;
+    //array where all valid Operators are saved, can be esily expanded
+    char oppArray[numberOfOperators] = { '+','-','*','/','=' };
+    char input;
+    bool validInput = false;
+
+    //Loops as long as input isn't valid, enters at least one time
+    while (!validInput) {
+        scanf_s("%c\n", &input);
+        //checks every position of the array if a position is equal to input returns the input, which also stopps the function
+        for (int i = 0; i <= numberOfOperators; i++) {
+            if (input == oppArray[i]) {
+                return input;
+            }
+        }
+        //if the input was deemed invalid it asks for new input and goes to the top of the while loop
+        printf("Diese Eigabe war nicht zulässig probieren sie es noch einmal!\n");
+    }
+}
\ No newline at end of file