diff --git a/Axel/src/de/hs_mannheim/informatik/spreadsheet/Spreadsheet.java b/Axel/src/de/hs_mannheim/informatik/spreadsheet/Spreadsheet.java
index ceacf6f..2241b80 100644
--- a/Axel/src/de/hs_mannheim/informatik/spreadsheet/Spreadsheet.java
+++ b/Axel/src/de/hs_mannheim/informatik/spreadsheet/Spreadsheet.java
@@ -37,12 +37,10 @@ public class Spreadsheet {
 	private String get(int row, int col) {
 		return cells[row][col].getValue();
 	}
-
 	public String get(String cellName) {
 		cellName = cellName.toUpperCase();
 		return get(getRow(cellName), getCol(cellName));
 	}
-
 	private void put(int row, int col, String value) {
 		if (!value.startsWith("="))
 			cells[row][col].setValue(value);
@@ -51,20 +49,16 @@ public class Spreadsheet {
 			evaluateCell(row, col);
 		}
 	}
-
 	public void put(String cellName, String value) {
 		cellName = cellName.toUpperCase();
 		put(getRow(cellName), getCol(cellName), value);
 	}
-
 	private int getCol(String cellName) {
 		return cellName.charAt(0) - 'A';
 	}
-
 	private int getRow(String cellName) {
 		return cellName.charAt(1) - '1';
 	}
-
 	// -----
 	// business logic
 
@@ -114,19 +108,19 @@ public class Spreadsheet {
 		String formula = cells[row][col].getFormula();
 		String result = "";
 
-		if (formula.startsWith("SUMME("))  // e.g. SUMME(A3:A8)
-			result = "" + sum(formula.substring(6, 8), formula.substring(9, 11));  // TODO adapt to cells with two digits
-		else if (formula.startsWith("PRODUKT("))  // e.g. PRODUKT(A3:B9)
+		if (formula.startsWith("SUMME(")) {  // e.g. SUMME(A3:A8)
+			result += sum(formula.substring(6, 8), formula.substring(9, 11)); 
+		}else if (formula.startsWith("PRODUKT(")) {  // e.g. PRODUKT(A3:B9)
 			result = "TODO"; // TODO
-		else if (formula.startsWith("MITTELWERT("))  // e.g. MITTELWERT(A3:A5)
+		}else if (formula.startsWith("MITTELWERT(")) {  // e.g. MITTELWERT(A3:A5)
 			result = "TODO"; // TODO
-		else if (formula.startsWith("STABW("))  // e.g. STABW(C6:D8) -> Standardabweichung
+		}else if (formula.startsWith("STABW(")) { // e.g. STABW(C6:D8) -> Standardabweichung
 			result = "TODO"; // TODO
-		else if (formula.startsWith("MIN("))  // e.g. MIN(C13:H13) -> größter Wert
+		}else if (formula.startsWith("MIN("))  {// e.g. MIN(C13:H13) -> größter Wert
 			result = "TODO"; // TODO
-		else if (formula.startsWith("MAX("))  // e.g. MAX(A1:A10) -> Standardabweichung
+		}else if (formula.startsWith("MAX(")) {  // e.g. MAX(A1:A10) -> Standardabweichung
 			result = "TODO"; // TODO
-		else if (!formula.isEmpty()) {
+		}else if (!formula.isEmpty()) {
 			try {
 				result = "" + calculate(formula);
 			} catch(ArithmeticException ae) {
@@ -144,9 +138,14 @@ public class Spreadsheet {
 	 * @return The sum calculated.
 	 */
 	private long sum(String startCellName, String endCellName) {
-		// TODO implement
-
-		return 0;
+		long res = 0;
+		for(int j = getRow(startCellName); j< (getRow(endCellName)+1);j++){
+			for(int i = getCol(startCellName); i< (getCol(endCellName)+1);i++) {
+				if(!cells[j][i].getValue().isBlank())
+					res += Long.parseLong(cells[j][i].getValue());
+			}
+		}
+		return res;
 	}
 
 	/**