diff --git a/src/main/res/raw/collections.forth b/src/main/res/raw/collections.forth
index d781bde..40032bc 100644
--- a/src/main/res/raw/collections.forth
+++ b/src/main/res/raw/collections.forth
@@ -85,6 +85,7 @@
 : remove ( l o -- l ) swap :remove/O jvm-call-method ;
 : keys ( d -- l ) :keys jvm-call-method ;
 : values ( d -- l ) :values jvm-call-method ;
+: sum ( c -- n ) 0 swap { + } each ;
 
 : ... ( lower upper step -- lst ) :com.vectron.fcl.types.Range/create/NNN jvm-call-static ;
 : .. ( lower upper -- lst ) 1  ... ;
diff --git a/src/main/res/raw/core.forth b/src/main/res/raw/core.forth
index d018bc3..de7b0e0 100644
--- a/src/main/res/raw/core.forth
+++ b/src/main/res/raw/core.forth
@@ -24,6 +24,7 @@
 : else immediate ['] jmp , (dummy) swap resolve ;
 : then immediate resolve ;
 : begin immediate here ;
+: again immediate ['] jmp , (offset) ;
 : while immediate ['] jmp#f , (dummy) ;
 : repeat immediate swap ['] jmp , (offset)  resolve ;
 : until immediate ['] jmp#f , (offset) ;
diff --git a/src/main/res/raw/misc.forth b/src/main/res/raw/misc.forth
index 45cd330..c5fcda6 100644
--- a/src/main/res/raw/misc.forth
+++ b/src/main/res/raw/misc.forth
@@ -17,4 +17,34 @@
 : tone ( hz ms -- ) swap :com.vectron.forthcalc.support.Tone/play/di jvm-call-static ;
 : torch ( n -- ) :com.vectron.forthcalc.support.Torch/toggle/O jvm-call-static ;
 
-: match: immediate ` lastword set-predicate ;
\ No newline at end of file
+: match: immediate ` lastword set-predicate ;
+
+: npv ( cashflow rate -- n )
+    -> rate 0 => year
+    { rate year @ dis year inc } map sum ;
+
+: npv* ( .. rate -- n ) >r list* r> npv ;
+
+: npv/npv' ( cashflow rate -- npv/npv' )
+    1+ -> rate 0 => n
+    0 0 rot {
+        dup  ( each ) n @ neg * rate n @ 1+ neg pow * ( npv' ) rot +
+        swap ( each ) rate n @ pow /                  ( npv  ) rot +
+        swap
+        n inc
+    } each / ;
+
+var: irr-guess 0 irr-guess !
+
+: irr ( cashflow -- n/nil )
+    -> cashflow irr-guess @ 100 / => guess
+    1000 0 do
+        guess @ cashflow guess @ npv/npv' - ( new guess )
+        dup guess @ - abs 0.01 < if
+            100 * unloop exit
+        then
+        guess !
+    loop
+    nil ;
+
+: irr* ( cashflow -- n ) list* irr ;
\ No newline at end of file
diff --git a/src/main/res/raw/ops.forth b/src/main/res/raw/ops.forth
index 09c9830..5ca91cb 100644
--- a/src/main/res/raw/ops.forth
+++ b/src/main/res/raw/ops.forth
@@ -18,7 +18,7 @@
         ( years ) 1 -
     repeat
     drop ( years ) r> r> 2drop ;
-: dis ( b i n -- t ) swap 100 / neg 1+ swap pow * ;
+: dis ( b i n -- t ) swap 100 / 1+ swap pow / ;
 : tip1 ( n -- n ) 15 percent ;
 : tip2 ( bill split --  total tip ) / dup 115 percent swap 15 percent ;
 ( trigonometry )
diff --git a/src/test/java/com/vectron/fcl/FclTest.java b/src/test/java/com/vectron/fcl/FclTest.java
index 734d7ef..26a86b1 100644
--- a/src/test/java/com/vectron/fcl/FclTest.java
+++ b/src/test/java/com/vectron/fcl/FclTest.java
@@ -67,6 +67,7 @@ public class FclTest {
 
     @After
     public void tearDown() throws Exception {
+        System.out.println("Transcript: " + transcript.content());
         assertEquals(0, fcl.stackSize());
         assertEquals(0, fcl.rStackSize());
         assertEquals(0, evalPop("psp @").longValue());
@@ -210,12 +211,19 @@ public class FclTest {
     @Test
     public void testFinance() {
         assertEquals(1216.65, evalPop("1000 4 5 cin1").doubleValue(), 0.01);
-        assertEquals(815.37, evalPop("1000 4 5 dis").doubleValue(), 0.01);
+        assertEquals(821.93, evalPop("1000 4 5 dis").doubleValue(), 0.01);
+        assertEquals(558.39, evalPop("1000 6 10 dis").doubleValue(), 0.01);
         evalDoubles("1000.0 4 5 100 cin2", asList(1000.0, 2240.0, 3529.6, 4870.784, 6265.61536, 7716.2399744));
         assertEquals(15, evalPop("100 tip1").doubleValue(), 0.01);
         evalDoubles("100 1 tip2", asList(115.0, 15.0));
         evalDoubles("100 3 tip2", asList(38.33, 5));
         evalDoubles("3421 5 tip2", asList(786.83, 102.63));
+        assertEquals(-371.68, evalPop("[ -1000 50 100 150 200 250 ] 5 npv").doubleValue(), 0.01);
+        assertEquals(-371.68, evalPop("-1000 50 100 150 200 250 5 npv*").doubleValue(), 0.01);
+        assertEquals(-250, evalPop("[ -1000 50 100 150 200 250 ] 0 npv").doubleValue(), 0.01);
+        assertEquals(12.006, evalPop("[ -500 50 100 150 200 250 ] irr").doubleValue(), 0.01);
+        assertEquals(-7.431, evalPop("[ -1000 50 100 150 200 250 ] irr").doubleValue(), 0.01);
+        assertEquals(-28.482, evalPop("-10 irr-guess ! -5000 200 230 400 202 450 irr*").doubleValue(), 0.01);
     }
 
     private void evalDoubles(String script, List<Number> expected) {
@@ -809,6 +817,8 @@ public class FclTest {
         assertEquals(true, evalPop("m 2 at").boolValue());
         assertEquals(1, evalPop("m 2 index-of").intValue());
         assertEquals(0, evalPop("m clear m size").intValue());
+        assertEquals(6, evalPop("[ 4 -1 3 ] sum").intValue());
+        assertEquals(1+2+3+4+5, evalPop("1 5 .. sum").intValue());
     }
 
     @Test