diff --git a/README.md b/README.md
index af172ae..2bcbaa3 100644
--- a/README.md
+++ b/README.md
@@ -10,12 +10,11 @@ Quick examples:
 
 - easy calculation with **stacked results**
 ```
-rpn> 1 exp 3 *
-8.1548454853771357061
+rpn> 1 2 +
+3
 rpn> 2 sqrt
-2> 8.1548454853771357061
+2> 3
 1> 1.4142135623730950488
-rpn> 
 ```
 
 - **programs** and **variables**, eg same example as in HP28S Quick Reference:
@@ -67,8 +66,6 @@ rpn>
 |uname |	show rpn complete identification string
 |type |	show type of stack first entry
 |default |	set float representation and precision to default
-|prec |	get float precision in bits when first stack is not a number, set float precision in bits when first stack entry is a number. ex: ```256 prec```
-|round|	set float rounding mode. Authoerized values are: ```["nearest", "toward zero", "toward +inf", "toward -inf", "away from zero"] round```. ex: ```"nearest" round```
 
 #### real
 
@@ -87,14 +84,17 @@ rpn>
 |sq|	(or sqr) square
 |mod|	modulo
 |abs|	absolute value
+|dec|	decimal representation
+|hex|	hexadecimal representation
+|prec |	get float precision in bits when first stack is not a number, set float precision in bits when first stack entry is a number. ex: ```256 prec```
+|round|	set float rounding mode. Authoerized values are: ```["nearest", "toward zero", "toward +inf", "toward -inf", "away from zero"] round```. ex: ```"nearest" round```
+|fact| n! for integer n or Gamma(x+1) for fractional x
+|sign| 1 if number at stack level 1 is > 0, 0 if == 0, -1 if <= 0
 
-#### real representation
+#### mode
 
 |keyword|description|
 |-|-|
-|dec|	decimal representation
-|hex|	hexadecimal representation
-|bin|	binary representation
 |std|	standard floating numbers representation. ex: [25] std
 |fix|	fixed point representation. ex: 6 fix
 |sci|	scientific floating point representation. ex: 20 sci
diff --git a/src/program.cpp b/src/program.cpp
index ce9521f..b95f27f 100644
--- a/src/program.cpp
+++ b/src/program.cpp
@@ -50,6 +50,8 @@ program::keyword_t program::s_keywords[] =
     { cmd_keyword, "prec", &program::precision, "get float precision in bits when first stack is not a number\n\t"
                                                 "set float precision in bits when first stack entry is a number. ex: 256 prec" },
     { cmd_keyword, "round", &program::round, "set float rounding mode.\n\tex: [\"nearest\", \"toward zero\", \"toward +inf\", \"toward -inf\", \"away from zero\"] round" },
+    { cmd_keyword, "fact", &program::fact, "n! for integer n or Gamma(x+1) for fractional x" },
+    { cmd_keyword, "sign", &program::sign, "1 if number at stack level 1 is > 0, 0 if == 0, -1 if <= 0" },
 
     //TEST
     { cmd_undef, "", NULL, "\nTEST"},
diff --git a/src/rpn-real.hpp b/src/rpn-real.hpp
index 2d87a5b..fc33f9d 100644
--- a/src/rpn-real.hpp
+++ b/src/rpn-real.hpp
@@ -150,3 +150,28 @@ void dec()
     ARG_MUST_BE_OF_TYPE(0, cmd_number);
     ((number*)_stack->back())->_representation = number::dec;
 }
+
+void fact()
+{
+    MIN_ARGUMENTS(1);
+    ARG_MUST_BE_OF_TYPE(0, cmd_number);
+
+    // fact(n) = gamma(n+1)
+    number* left = (number*)_stack->back();
+    number* right = (number*)_stack->allocate_back(number::calc_size(), cmd_number);
+    right->_value = 1L;
+    plus();
+
+    CHECK_MPFR(mpfr_gamma(left->_value.mpfr, left->_value.mpfr, floating_t::s_mpfr_rnd));
+}
+
+void sign()
+{
+    MIN_ARGUMENTS(1);
+    ARG_MUST_BE_OF_TYPE(0, cmd_number);
+
+    // fact(n) = gamma(n+1)
+    number* left = (number*)_stack->back();
+    int result = mpfr_sgn(left->_value.mpfr);
+    left->_value = (long)result;
+}
diff --git a/test/06-real.txt b/test/06-real.txt
index d241f42..7e9e5ed 100644
--- a/test/06-real.txt
+++ b/test/06-real.txt
@@ -332,4 +332,30 @@ abs
 -> error should be 2
 erase
 
+# fact (1)
+6 fact
+-> stack should be 720
+erase
+
+# fact (2)
+'r' fact
+-> error should be 3
+-> stack size should be 1
+erase
+
+# fact (3)
+fact
+-> error should be 2
+erase
+
+# sign (1)
+23 sign -34 sign 0 sign
+-> stack should be 1, -1, 0
+erase
+
+# sign (2)
+sign
+-> error should be 2
+erase
+
 default