Ever wonder how a stock or an index like the Dow Jones Industrials is doing at the moment, priced in gold? Is it up or down from yesterday? How much?
To do this the "old school" way, you would collect four numbers: the price of gold and the price of the security at the previous trading day's close, and their current prices, all in the same currency. Calculate the previous closing price of the currency unit (USD, GBP, JPY, EUR, etc.) by dividing 31.1035 by the gold price, giving the value of the currency unit in gold grams. Do the same with the current price of gold. Then multiply the prior closing price of the security by the prior closing value of the currency to get the previous gold price of the security. Multiply the current price of the security by the current value of the currency to get the current gold price of the security. Now subtract the security's prior close from its current price to get the gain or loss in gold grams. Divide this value by the gold price of the security for the previous day to see the percentage gain or loss.
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