They probably don't even exist now.
You put a penny in the scale, you get on the scale, it shows your weight in pounds.

It allows you to just weigh once.

>Dan,
>
>What's "a penny scale"?
>
>>Part 1.
>>
>>You have 10 bags of 1000 gold coins each.
>>One of the bags is fake gold and each coin weighs 1.1 lb.
>>The other bags contain real gold and each coin weighs 1.2 lb.
>>
>>You have one penny to use on a penny scale.
>>( No tricks, using gum and a string to pull the penny back out :) )
>>
>>How can you weigh the gold in such a way that you can determine which bag has the fake gold.
>>
>>
>>Part 2
>>
>>This problem is the same as above, but there is at least one bag of real gold. There could be as many as 10 with real gold.
>>
>>How do you weigh the gold in such a way to determine which bags have the real gold?