function reckoner(start,tolevel,havelvl)
   local x = start
   local lvl,y = {}
   local havelvl = havelvl or {}
   if 2 <= tolevel*1 then
      y = x%4
      x=(x-y)*3/4
      lvl[1] = y
      if havelvl[2] then
         x=x+havelvl[2]
      end
   end
   if 3 <= tolevel*1 then
      y = x%3
      x=(x-y)*2/3
      lvl[2] = y
      if havelvl[3] then
         x=x+havelvl[3]
      end
   end
   if 4 <= tolevel*1 then
      y = x%3
      x=(x-y)*2/3
      lvl[3] = y
      if havelvl[4] then
         x=x+havelvl[4]
      end
   end
   if 5 <= tolevel*1 then
      y = x%3
      x=(x-y)*2/3
      lvl[4] = y
      if havelvl[5] then
         x=x+havelvl[5]
      end
   end
   if 6 <= tolevel*1 then
      y = x%2
      x=(x-y)*1/2
      lvl[5] = y
      if havelvl[6] then
         x=x+havelvl[6]
      end
   end
   echo("SHIP TRADE RECKONER!\n")
   echo(x.." final product at level ".. (tolevel*1>6 and 6 or tolevel))
   echo("\nRemainders:\n")
   local remainder = false
   for i=1,5 do
      if lvl[i] ~= 0 then
         echo(lvl[i] .." level ".. i .." items left.\n")
         remainder = true
      end
   end
   if not remainder then echo("NONE!") end
end


--Example:

reckoner(60,5,{[4]=1,[5]=3})

--[[
Translation: Starting with 60 level 1 items, going to level 5 item. Already have one level 4 item, and 3 level 5 items.

shows:

SHIP TRADE RECKONER!
17 final product at level 5
Remainders:
NONE!

Item levels:

Lvl 1                                      Lvl 4
Wool                                       Incense
Fur                                        Porcelain
Grain                                      Silk
Ore                                        Wine
Salt
Sandstone
Cotton

Lvl 2                                      Lvl 5
Sugar                                      Perfume
Fruits                                     Tabac
Honey                                      Armaments
Granite
Terracotta
Hemp

Lvl 3                                      Lvl 6
Kawhe                                      Gems
Glass                                      Spices
Ceramics
Marble
Tea