In a currency exchange rate what is the maximum number of decimal places used?

currency, currency-exchange-rates, decimal, sql, t-sql

Solution

I once worked on an international financial C# based package, which had to support numerous currencies, and we supported 6 decimal places. We had a couple of very experienced designers who told us that would be sufficient.

Problem

I need to store currency exchange rate data in the SQL 2008 database. I would like to keep rate as a `decimal` data type in the database. One thing I am not sure about, is how many decimal places to give (e.g. decimal(18, ?)). Since, I will be using this service as a source: http://openexchangerates.org/latest.json. There, it seems that the highest number of decimal places used is '6'. Is that the right number, or there possibly can be rates with more than 6 decimal places?

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