diff --git a/include/real.cpp b/include/real.cpp
index ba6d914d7..180a63743 100755
--- a/include/real.cpp
+++ b/include/real.cpp
@@ -79,6 +79,26 @@ bool real::is_real (const char *s)
   return ok;
 }
 
+bool real::is_natural (const char *s)
+{
+  bool ok = s && *s != '\0';
+  if (ok)
+  {
+    while (*s == ' ')
+      s++;                    // Remove leading spaces before
+
+    if (*s)
+    {
+      while (isdigit(*s))
+        s++;          
+      ok = *s == '\0';
+    }
+    else ok = FALSE;
+    
+  }
+  return ok;
+}
+
 real::real (const char *s)
 {
   if (s)
diff --git a/include/real.h b/include/real.h
index 5a90711fd..839cb57ba 100755
--- a/include/real.h
+++ b/include/real.h
@@ -34,6 +34,7 @@ public:
   static char* eng2ita(char* s);
   static char* ita2eng(const char* s);
   static bool is_real(const char* n);
+  static bool is_natural(const char* n);
 
   // @FPUB
   DEC* ptr() const { return (DEC*)&_dec; }