--- C:/D/eclipseworkspaces/Trial/jakarta-poi/src/java/org/apache/poi/hssf/usermodel/HSSFCell.java	(revision 411790)
+++ C:/D/eclipseworkspaces/Trial/jakarta-poi/src/java/org/apache/poi/hssf/usermodel/HSSFCell.java	(working copy)
@@ -597,8 +597,9 @@ 
         } else {
             setCellType(CELL_TYPE_FORMULA,false,row,col,styleIndex);
             FormulaRecordAggregate rec = (FormulaRecordAggregate) record;
-            rec.getFormulaRecord().setOptions(( short ) 2);
-            rec.getFormulaRecord().setValue(0);
+            FormulaRecord frec = rec.getFormulaRecord();
+            frec.setOptions(( short ) 2);
+            frec.setValue(0);
             
             //only set to default if there is no extended format index already set
             if (rec.getXFIndex() == (short)0) rec.setXFIndex(( short ) 0x0f);
@@ -607,9 +608,15 @@ 
             Ptg[] ptg  = fp.getRPNPtg();
             int   size = 0;
             //System.out.println("got Ptgs " + ptg.length);
+            
+            // clear the Ptg Stack
+            for (int i=0, iSize=frec.getNumberOfExpressionTokens(); i<iSize; i++) {
+                frec.popExpressionToken();
+            }
+            
             for (int k = 0; k < ptg.length; k++) {
                 size += ptg[ k ].getSize();
-                rec.getFormulaRecord().pushExpressionToken(ptg[ k ]);
+                frec.pushExpressionToken(ptg[ k ]);
             }
             rec.getFormulaRecord().setExpressionLength(( short ) size);
             //Workbook.currentBook = null;
--- C:/D/eclipseworkspaces/Trial/jakarta-poi/src/java/org/apache/poi/hssf/model/FormulaParser.java	(revision 411790)
+++ C:/D/eclipseworkspaces/Trial/jakarta-poi/src/java/org/apache/poi/hssf/model/FormulaParser.java	(working copy)
@@ -229,16 +229,35 @@ 
     }
     
     
+    /** Get the exponent for numbers of form 1.3E21 */
+    private String GetExponent() {
+        StringBuffer retval = new StringBuffer();
+        String sign = "";
+        GetChar();
+        if ('-' == look) {
+            sign = "-";
+            GetChar();
+        }
+        while (IsDigit(look)) {
+            retval.append(look);
+            GetChar();
+        }
+        if (retval.length() > 0) {
+            retval.insert(0, sign);
+        }
+        return retval.toString();
+    }
+    
     /** Get a Number */
     private String GetNum() {
-        String Value ="";
+        StringBuffer value = new StringBuffer();
         if  (!IsDigit(look)) Expected("Integer");
         while (IsDigit(look)){
-            Value = Value + look;
+            value.append(look);
             GetChar();
         }
         SkipWhite();
-        return Value;
+        return value.toString();
     }
 
     /** Output a String with Tab */
@@ -482,8 +501,18 @@ 
                 Match('.');
                 String decimalPart = null;
                 if (IsDigit(look)) number = number +"."+ GetNum(); //this also takes care of someone entering "1234."
+                if ('E' == look) {
+                    String exponent = GetExponent();
+                    number += 'E' + exponent;
+                }
                 tokens.add(new NumberPtg(number));
-            } else {
+            } 
+            else if ('E' == look) {
+                String exponent = GetExponent();
+                number += 'E'+exponent;
+                tokens.add(new NumberPtg(number));
+            }
+            else {
                 tokens.add(getNumberPtgFromString(number));  //TODO:what if the number is too big to be a short? ..add factory to return Int or Number!
             }
         }
--- C:/D/eclipseworkspaces/Trial/jakarta-poi/src/testcases/org/apache/poi/hssf/model/TestFormulaParser.java	(revision 411790)
+++ C:/D/eclipseworkspaces/Trial/jakarta-poi/src/testcases/org/apache/poi/hssf/model/TestFormulaParser.java	(working copy)
@@ -17,6 +17,8 @@ 
         
 package org.apache.poi.hssf.model;
 
+import java.io.FileOutputStream;
+
 import junit.framework.TestCase;
 
 import org.apache.poi.hssf.record.formula.AbstractFunctionPtg;
@@ -38,6 +40,7 @@ 
 import org.apache.poi.hssf.record.formula.UnaryMinusPtg;
 import org.apache.poi.hssf.record.formula.UnaryPlusPtg;
 import org.apache.poi.hssf.usermodel.HSSFCell;
+import org.apache.poi.hssf.usermodel.HSSFRichTextString;
 import org.apache.poi.hssf.usermodel.HSSFRow;
 import org.apache.poi.hssf.usermodel.HSSFSheet;
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
@@ -404,7 +407,70 @@ 
 		
 	}
 
-     public static void main(String [] args) {
+    // bug 38396 : Formula with exponential numbers not parsed correctly.
+    public void testExponentialParsing() {
+        FormulaParser fp = new FormulaParser("1.3E21/2", null);
+        fp.parse();
+        Ptg[] ptgs = fp.getRPNPtg();
+        assertTrue("three tokens expected, got "+ptgs.length,ptgs.length == 3);
+        assertTrue("NumberPtg",(ptgs[0] instanceof NumberPtg));
+        assertTrue("IntPtg",(ptgs[1] instanceof IntPtg));
+        assertTrue("DividePtg",(ptgs[2] instanceof DividePtg));
+
+        fp = new FormulaParser("1322E21/2", null);
+        fp.parse();
+        ptgs = fp.getRPNPtg();
+        assertTrue("three tokens expected, got "+ptgs.length,ptgs.length == 3);
+        assertTrue("NumberPtg",(ptgs[0] instanceof NumberPtg));
+        assertTrue("IntPtg",(ptgs[1] instanceof IntPtg));
+        assertTrue("DividePtg",(ptgs[2] instanceof DividePtg));
+
+        fp = new FormulaParser("1.3E1/2", null);
+        fp.parse();
+        ptgs = fp.getRPNPtg();
+        assertTrue("three tokens expected, got "+ptgs.length,ptgs.length == 3);
+        assertTrue("NumberPtg",(ptgs[0] instanceof NumberPtg));
+        assertTrue("IntPtg",(ptgs[1] instanceof IntPtg));
+        assertTrue("DividePtg",(ptgs[2] instanceof DividePtg));
+
+    }
+    public void testExponentialInSheet() throws Exception {
+        HSSFWorkbook wb = new HSSFWorkbook();
+        
+        wb.createSheet("Cash_Flow");;
+        
+        HSSFSheet sheet = wb.createSheet("Test");
+        HSSFRow row = sheet.createRow(0);
+        HSSFCell cell = row.createCell((short)0);
+        String formula = null;
+
+        cell.setCellFormula("1.3E21/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "1.3E21/3", formula);
+        
+        cell.setCellFormula("1322E21/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "1.322E24/3", formula);
+
+        cell.setCellFormula("1.3E1/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "13.0/3", formula);
+
+        cell.setCellFormula("1.3E-4/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "1.3E-4/3", formula);
+
+        cell.setCellFormula("13E-15/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "1.3E-14/3", formula);
+
+        cell.setCellFormula("1.3E3/3");
+        formula = cell.getCellFormula();
+        assertEquals("Exponential formula string", "1300.0/3", formula);
+        
+    }
+
+    public static void main(String [] args) {
         System.out.println("Testing org.apache.poi.hssf.record.formula.FormulaParser");
         junit.textui.TestRunner.run(TestFormulaParser.class);
     }