diff --git a/Makefile b/Makefile
index 116538c..9572506 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,10 @@ abCalcExprReal.o: abCalcExpr.h abCalcExprReal.h
 abCalcStack.o: abCalcExpr.h abCalcStack.h
 abCalcMode.o: abCalcMode.h abCalcExpr.h
 abCalcExprInt.o: abCalcExpr.h abCalcMode.h abCalcExprInt.h
-abCalc.o: abCalcExpr.h abCalcMode.h abCalcExprReal.h abCalcExprInt.h abCalcStack.h
+abCalc.o: abCalc.h abCalcExpr.h abCalcMode.h abCalcExprReal.h abCalcExprInt.h abCalcStack.h
+abCalcMain.o: abCalc.h abCalcStack.h abCalcExpr.h
+
+CFLAGS=-g
 
 $(NAME): $(OBJS)
 	cc -o $(NAME) $(OBJS)
diff --git a/abCalcExprReal.c b/abCalcExprReal.c
index 96b81b5..d73fda8 100644
--- a/abCalcExprReal.c
+++ b/abCalcExprReal.c
@@ -4,6 +4,7 @@
  */
 
 
+#include <math.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
@@ -101,6 +102,17 @@ abCalcExpr *abCalcExprRealParse(abCalcExpr *expr, char *buffer)
 
 char *abCalcExprRealFormat(abCalcExpr *expr, char *buffer)
 {
+	abCalcRealType exp;
+	abCalcRealType value;
+    char format[16];
+    int numDecDigits;
+	int periodPos = -1;
+	int zerosStart = -1;
+	int spaceStart = -1;
+	int expPos = -1;
+    int len;
+    int i;
+
     if (expr == NULL)
         return NULL;
 
@@ -110,6 +122,86 @@ char *abCalcExprRealFormat(abCalcExpr *expr, char *buffer)
     if (expr->type != abCalcExprTypeReal)
         return NULL;
 
-    sprintf(buffer, "%f", expr->u.real);
+    value = expr->u.real;
+
+	if (value == 0.0) {
+		exp = 0.0;
+	} else {
+		exp = floor(log10(fabs(value)));
+	}
+	
+	if (exp >= 0)
+		exp++;
+	
+	if ((exp > 12) ||
+		(exp < -12)) {
+		strcpy(format, "%-25.11E");
+	} else if (exp <= -2) {
+		double shiftedValue = value * 1.0e12;
+		if (shiftedValue == floor(shiftedValue)) {
+			strcpy(format, "%-18.12f");
+		} else {
+			strcpy(format, "%-25.11E");
+		}
+	} else {
+		int numDecDigits = (int)(12 - exp);
+		if (numDecDigits > 12) {
+			numDecDigits = 12;
+		}
+		sprintf(format, "%%-28.%df", numDecDigits);
+	}
+
+    sprintf(buffer, format, value);
+    len = strlen(buffer);
+
+	for (i = 0; i < len; i++) {
+		switch (buffer[i]) {
+			case '.':
+				periodPos = i;
+				break;
+
+			case '0':
+				if (expPos != -1) {
+					break;
+				}
+				if ((periodPos != -1) &&
+					(zerosStart == -1)) {
+					if (periodPos == i - 1) {
+						zerosStart = periodPos;
+					} else {
+						zerosStart = i;
+					}
+				}
+				break;
+			case 'E':
+				expPos = i;
+				break;
+			case ' ':
+				spaceStart = i;
+				break;
+			default:
+				if (expPos == -1)
+					zerosStart = -1;
+				break;
+		}
+		if (spaceStart != -1)
+			break;
+	}
+	
+	if (spaceStart != -1) {
+        buffer[spaceStart] = '\0';
+        len = spaceStart;
+	}
+	
+	if (zerosStart != -1) {
+		if (expPos != -1) {
+            memmove(&buffer[zerosStart], &buffer[expPos], len - expPos + 1);
+			len = expPos - zerosStart;
+        }
+		else {
+			buffer[zerosStart] = '\0';
+        }
+	}
+	
     return buffer;
 }
diff --git a/abCalcMain.c b/abCalcMain.c
index b5398b5..7ba3c91 100644
--- a/abCalcMain.c
+++ b/abCalcMain.c
@@ -1,9 +1,58 @@
+/* 
+    abCalcMain.c
+        By: Jeremy Rand
+ */
+
+
 #include <stdio.h>
+#include <string.h>
 #include <stdlib.h>
 
+#include "abCalc.h"
+#include "abCalcExpr.h"
+#include "abCalcStack.h"
+
+
+char gBuffer[AB_CALC_EXPR_STRING_MAX];
+abCalcExpr gExpr;
+
 
 int main(void)
 {
-    printf("Hello, world!\n");
+    int timeToQuit = 0;
+    int depth;
+    int item;
+    int len;
+
+    abCalcInit();
+
+    while (!timeToQuit) {
+        printf("Stack:\n");
+        depth = abCalcStackNumItems();
+
+        if (depth == 0) {
+            printf("    Empty!\n");
+        } else {
+            for(item = depth - 1; item >= 0; item--) {
+                abCalcFormatExpr(abCalcStackExprAt(item), gBuffer);
+                printf("    %3d: %s\n", item + 1, gBuffer);
+            }
+        }
+
+        timeToQuit = 1;
+        if (fgets(gBuffer, sizeof(gBuffer), stdin) != NULL) {
+            len = strlen(gBuffer);
+            if ((gBuffer[len - 1] == '\r') ||
+                (gBuffer[len - 1] == '\n')) {
+                gBuffer[len - 1] = '\0';
+            }
+
+            if ((abCalcParseExpr(&gExpr, gBuffer) != NULL) &&
+                (abCalcStackExprPush(&gExpr) != NULL)) {
+                timeToQuit = 0;
+            }
+        }
+    }
+
     exit(0);
 }
diff --git a/abCalcStack.c b/abCalcStack.c
index a10f576..07fc886 100644
--- a/abCalcStack.c
+++ b/abCalcStack.c
@@ -54,11 +54,10 @@ int abCalcStackNumItems(void)
 }
 
 
-abCalcExpr *abCalcStackExprAt(abCalcExpr *expr, int depth)
+abCalcExpr *abCalcStackExprAt(int depth)
 {
     abCalcExpr *result = NULL;
-    if ((depth < gStackNumItems) &&
-        (expr != NULL)) {
+    if (depth < gStackNumItems) {
         result = &(gStack[gStackNumItems - 1 - depth]);
     }
 
diff --git a/abCalcStack.h b/abCalcStack.h
index 0346029..9e7dba3 100644
--- a/abCalcStack.h
+++ b/abCalcStack.h
@@ -16,7 +16,7 @@ abCalcExpr *abCalcStackExprPush(abCalcExpr *expr);
 
 abCalcExpr *abCalcStackExprPop(abCalcExpr *expr);
 
-abCalcExpr *abCalcStackExprAt(abCalcExpr *expr, int depth);
+abCalcExpr *abCalcStackExprAt(int depth);
 
 int abCalcStackNumItems(void);