diff --git a/Expression.asm b/Expression.asm
index a8500aa..a79d1f3 100644
--- a/Expression.asm
+++ b/Expression.asm
@@ -90,7 +90,7 @@ dv3      asl   ans                      roll up the next number
          rol   ans+6
          sec                            subtract for this digit
          lda   ans+4
-         sbc   num1
+         sbc   num2
          tax
          lda   ans+6
          sbc   num2+2
@@ -267,7 +267,7 @@ dv3      asl   ans                      roll up the next number
          rol   ans+6
          sec                            subtract for this digit
          lda   ans+4
-         sbc   num1
+         sbc   num2
          tax
          lda   ans+6
          sbc   num2+2