diff --git a/Ide/IDE.icl b/Ide/IDE.icl
index 40dfa6b33be71bd05a746119e872272261699bf3..f9ab72f895ab81159e65230a5749c12e90aa2964 100644
--- a/Ide/IDE.icl
+++ b/Ide/IDE.icl
@@ -985,6 +985,8 @@ editMenu altgr_workaround mEditId editRecId mFileSaveId mFileRevertId {mn_und, m
 		:+: MenuItem "Add Pre&fix"		[ MenuId (mg_edt!!5), MenuFunction (noLS add_prefix_selection)]
 		:+: MenuItem "Remove Pref&ix"	[ MenuId (mg_edt!!6), MenuFunction (noLS rem_prefix_selection)]
 		:+: MenuItem "Change Prefi&x..."	[ MenuId (mg_edt!!7), MenuFunction (noLS change_prefix_dlog)]
+		:+: MenuItem "I&ncrement Integers"	[ MenuId (mg_edt!!8), MenuFunction (noLS increment_integers_in_selection)]
+		:+: MenuItem "De&crement Integers"	[ MenuId (mg_edt!!9), MenuFunction (noLS decrement_integers_in_selection)]
 		:+: MenuSeparator []
 		:+: MenuItem "Next &Window"
 			[ MenuModsFunction stackfun
diff --git a/Ide/IdeState.icl b/Ide/IdeState.icl
index 84981d16db876eb2485f7551faeaf20c56696d78..c70876e3b0eee59a72d74f3f9b05570783e18a1c 100644
--- a/Ide/IdeState.icl
+++ b/Ide/IdeState.icl
@@ -202,7 +202,7 @@ iniGeneral
 		(mEdCopyId,env)	= openId env
 		(mEdPasteId,env)	= openId env
 		(mEdClearId,env)	= openId env
-		(edToolsIds,env)	= openIds 8 env
+		(edToolsIds,env)	= openIds 10 env
 		(mdCmpId,env)	= openId env
 		(mdChkId,env)	= openId env
 		(mdGenId,env)	= openId env
diff --git a/Ide/prefix.dcl b/Ide/prefix.dcl
index 96ffe406dbf78dcdb26b2f6a7e22338275ffe0f8..718d5d61f7f8371c1a81115878f0ae70973a5fc1 100644
--- a/Ide/prefix.dcl
+++ b/Ide/prefix.dcl
@@ -17,3 +17,7 @@ shift_selection_right	:: !*(PSt General) -> *PSt General
 
 shift_selection_left	:: !*(PSt General) -> *PSt General
 // block outdent
+
+increment_integers_in_selection :: !*(PSt General) -> *PSt General
+
+decrement_integers_in_selection :: !*(PSt General) -> *PSt General
diff --git a/Ide/prefix.icl b/Ide/prefix.icl
index 89afb45081e6eecde9502f9af214080d70f9fffc..25dc12cc7d285ecf3ef56eabb5ab2d8797c24203 100644
--- a/Ide/prefix.icl
+++ b/Ide/prefix.icl
@@ -193,3 +193,84 @@ where
 		| n_spaces < size string && string.[n_spaces] == ' '
 			= count_spaces_at_begin (inc n_spaces) string
 		= n_spaces
+
+increment_integers_in_selection :: !*(PSt General) -> *PSt General
+increment_integers_in_selection ps
+	= replace_lines_and_redraw increment_prefix ps
+where
+	increment_prefix text_tab_width line
+		= increment_integers 0 line
+
+	increment_integers i line
+		| i<size line
+			| line.[i]<'0' || line.[i]>'9'
+				= increment_integers (i+1) line
+				# after_digits_i = skip_digits (i+1) line
+				| not (i>0 && line.[i-1]=='-')
+					# (n_extra_chars,line) = increment_integer (after_digits_i-1) i line
+					= increment_integers (after_digits_i+n_extra_chars) line
+					# after_zeros_i = skip_zeros i line
+					| after_digits_i==after_zeros_i
+						# line = line % (0,i-2) +++ "1" +++ line % (after_zeros_i,size line-1)
+						= increment_integers i line
+					| after_digits_i==i+1 && line.[i]=='1'
+						# line = line % (0,i-2) +++ "0" +++ line % (after_digits_i,size line-1)
+						= increment_integers i line
+					# (n_extra_chars,line) = decrement_integer (after_digits_i-1) i line
+					= increment_integers (after_digits_i+n_extra_chars) line
+			= line
+
+decrement_integers_in_selection :: !*(PSt General) -> *PSt General
+decrement_integers_in_selection ps
+	= replace_lines_and_redraw decrement_prefix ps
+where
+	decrement_prefix text_tab_width line
+		= decrement_integers 0 line
+
+	decrement_integers i line
+		| i<size line
+			| line.[i]<'0' || line.[i]>'9'
+				= decrement_integers (i+1) line
+			# after_digits_i = skip_digits (i+1) line
+			| not (i>0 && line.[i-1]=='-')
+				# after_zeros_i = skip_zeros i line
+				| after_digits_i==after_zeros_i
+					# line = line % (0,i-1) +++ "-1" +++ line % (after_zeros_i,size line-1)
+					= decrement_integers (i+2) line
+				| after_digits_i==i+1 && line.[i]=='1'
+					= decrement_integers (i+1) (line:=(i,'0'))
+				# (n_extra_chars,line) = decrement_integer (after_digits_i-1) i line
+				= decrement_integers (after_digits_i+n_extra_chars) line
+				# (n_extra_chars,line) = increment_integer (after_digits_i-1) i line
+				= decrement_integers (after_digits_i+n_extra_chars) line
+			= line
+
+increment_integer :: !Int !Int !{#Char} -> (!Int,!{#Char})
+increment_integer digit_i first_digit_i line
+	# digit = line.[digit_i]
+	| digit<>'9'
+		= (0,line:=(digit_i,inc digit))
+	| digit_i<>first_digit_i
+		= increment_integer (digit_i-1) first_digit_i (line:=(digit_i,'0'))
+		= (1,line % (0,digit_i-1) +++ "10" +++ line % (digit_i+1,size line-1))
+
+decrement_integer :: !Int !Int !{#Char} -> (!Int,!{#Char})
+decrement_integer digit_i first_digit_i line
+	# digit = line.[digit_i]
+	| digit>'1'
+		= (0,line:=(digit_i,dec digit))
+	| digit=='1'
+		| digit_i<>first_digit_i
+			= (0,line:=(digit_i,dec digit))
+			= (-1,line % (0,digit_i-1)+++line % (digit_i+1,size line-1))
+		= decrement_integer (digit_i-1) first_digit_i (line:=(digit_i,'9'))
+
+skip_digits i line
+	| i<size line && (line.[i]>='0' && line.[i]<='9')
+		= skip_digits (i+1) line
+		= i;
+
+skip_zeros i line
+	| i<size line && line.[i]=='0'
+		= skip_zeros (i+1) line
+		= i;