diff --git a/subtraction/sub b/subtraction/sub
index e21b79f..58e44d1 100755
--- a/subtraction/sub
+++ b/subtraction/sub
@@ -20,20 +20,24 @@ borrow(){
   b="${1%$2}"; b="${b#${3%?}}"
   [ "$b" -gt 0 ] && {
     c1="$2";
+    o="${1%$b$2}"; #echo "++ ${o} $((b-1)) $((c1+90))/$c1"
     [ "$b" -eq 10 ] && {
-      o="${1%$b$2}"; : $((b-=1)); o="${o}0${b}$c1" # eg 21 = 2090 10
+      : $((b-=1)); o="${o}0${b}$c1" # eg 21 = 2090 10
       # tbh idk why this works; 2090 should acctually be 1 10 9 10
       # which somehow becomes 209 10 ? I'm guessing a second borrow call is made
       # and that somehow corrects it; but again idk; a second borrow call /is/ made
       # but idk how it corrects it
     } || {
-      o="${1%$b$2}"; : $((b-=1)); o="$o$b$c1"
+      : $((b-=1)); [ "$4" != ":" -a "$4" ] && {
+        o="$o$b$((c1+90))"
+      } || o="$o$b$c1"
     }
     : $((c1+=10))
     echo "$o $c1"
   } || { # otherwise use recusion
     o="${1#${3%?}}"; o="${o%$2}"
-    borrow "$1" "$o" "${3%?}"
+    #echo "| $1 $o ${3%?}"
+    borrow "$1" "$o" "${3%?}" "${4}:"
   }
 }
 [ -z "${1##*.*}" -o -z "${2##*.*}" ] && {