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[Hortun]

Background

Hi everyone. I haven't played DF since ~2010 ish and have been playing the new Steam edition.

I noticed a fairly easy way to significantly improve trades involving bins of goods. I searched the forum and wiki, and maybe I used bad keywords or overlooked it, but I didn't see this documented anywhere, so I figured I'd mention it here. Please let me know if you have more information.

Also:

• I'm not sure if this is considered a bug or exploit, and if it would be worth reporting on the bug tracker.
• I'm not sure where to add this to the wiki. Maybe under "Trading" somewhere?

Observations / Steps to reproduce

• A trader is at your depot with at least one bin of items you want.
• The items in the bin are low value, and the bin's total value rounds up unfavorably. (Screenshot: cloth has combined value of 190 ☼, but trading the whole bin is valued at 1000 ☼)
• Selecting the whole bin trades at the unfavorable price.
• Select all but one item in the bin individually. Ideally leave the lowest value item unselected to reduce the rounding issue for the next step. Execute the trade. (Note: selecting all items in the bin will update the selection to include the whole bin at the unfavorable price.)
• Now select the bin with only one remaining item. The rounding is no longer as severely unfavorable, as it contains only a single low value item.

Note in the example screenshots above, we were able to purchase the bin in two trades; one trade at 150 ☼, then one for 50 ☼. Compared to selecting the whole bin, we save 800 ☼, or 80%.


Notes

I tested this in DF steam edition, v50.03. If folks want my save file, lmk and I can upload it; I manually saved before and after trading.

I'm speculating that:

• Rounding occurs on orders of magnitude (e.g. base ten units; 10, 100, 1000, etc)
• Some skills of your dwarf and possibly the trader may influence rounding. (completely guessing on this, no data)

Also note that trader skills increase per trade by 50 regardless of the trade size. Depending on your patience, many trades of small quantities could help level up your trader's skills and yield better trade values. (not tested, going off this wiki section: https://dwarffortresswiki.org/index.php/Trading#Miscellaneous_trading_advice)

Please let me know if you have additional info regarding rounding mechanics, or if I should add this to any particular place in the wiki! Or likewise, if I should report this as a bug or exploit.

[Afghani84]

AFAIK this is not a bug but simply due to rounding and the skill of your trader. I usually start forts with one dwarf as a novice appraiser and there you have the same issues with created wealth. A value like 200☼ for e.g. "Other Objects" is shown as 1.000☼ simply due to rounding.

[Felius]

I'm fairly sure that the traders will refuse to trade if they aren't actually making a profit without the rounding. Or rather, a few early caravans that listed the trader making the profit had them refuse to complete the trade with the justification that they had to make at least some profit.