Incrementing / decrementing numbers

define-command -hidden -params2 inc %{try %{evaluate-commands%sh{        ["$1"= 0 ]&& count=1|| count="$1"printf'%s%s''exec h"_/\d<ret><a-i>na'"$2($count)<esc>|{<space>cat<semicolon>echo<semicolon>}|bc<ret>"    }}catch %{execute-keys l}}mapglobal normal <c-a>': inc %val{count} +<ret>'mapglobal normal <c-x>': inc %val{count} -<ret>'

Creating a quick math prompt

mapglobal normal =': prompt math: %{exec "a%val{text}<lt>esc>|{ cat; echo; }|bc<lt>ret>"}<ret>'