Index: src/java/org/apache/poi/hssf/record/formula/eval/FunctionEval.java
===================================================================
--- src/java/org/apache/poi/hssf/record/formula/eval/FunctionEval.java	(revision 927787)
+++ src/java/org/apache/poi/hssf/record/formula/eval/FunctionEval.java	(working copy)
@@ -152,7 +152,7 @@
 		retval[184] = NumericFunction.FACT;
 
 		retval[190] = LogicalFunction.ISNONTEXT;
-
+		retval[197] = NumericFunction.TRUNC;
 		retval[198] = LogicalFunction.ISLOGICAL;
 
 		retval[212] = NumericFunction.ROUNDUP;
Index: src/java/org/apache/poi/hssf/record/formula/functions/NumericFunction.java
===================================================================
--- src/java/org/apache/poi/hssf/record/formula/functions/NumericFunction.java	(revision 927787)
+++ src/java/org/apache/poi/hssf/record/formula/functions/NumericFunction.java	(working copy)
@@ -26,6 +26,7 @@
 /**
  * @author Amol S. Deshmukh < amolweb at ya hoo dot com >
  * @author Josh Micich
+ * @author Stephen Wolke (smwolke at geistig.com)
  */
 public abstract class NumericFunction implements Function {
 
@@ -321,7 +322,28 @@
 			return MathX.roundUp(d0, (int)d1);
 		}
 	};
+	static final NumberEval TRUNC_ARG2_DEFAULT = new NumberEval(0);
+	public static final Function TRUNC = new Var1or2ArgFunction() {
 
+		public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0) {
+			return evaluate(srcRowIndex, srcColumnIndex, arg0, TRUNC_ARG2_DEFAULT);
+		}
+
+		public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1) {
+			double result;
+			try {
+				double d0 = singleOperandEvaluate(arg0, srcRowIndex, srcColumnIndex);
+				double d1 = singleOperandEvaluate(arg1, srcRowIndex, srcColumnIndex);
+				double multi = Math.pow(10d,d1);
+				result = Math.floor(d0 * multi) / multi;
+				checkValue(result);
+			}catch (EvaluationException e) {
+				return e.getErrorEval();
+			}
+			return new NumberEval(result);
+		}
+	};
+
 	/* -------------------------------------------------------------------------- */
 
 	private static final class Log extends Var1or2ArgFunction {