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What is the Difference between Additive notation and Subtractive notation in Roman numerals?

correct me if im wrong but this is an example of Additive: XXXIII = 10 + 10 + 10 + 1 + 1 + 1 = 33

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    Yes, that’s an example of additive notation. IX $=10-1=9$ is an example of subtractive notation, as is XC $=100-10=90$. Roman numerals were originally entirely additive; the subtractive notation was a later development.2012-05-23
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    Thanks for that you made it really clear :)2012-05-23
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    @BrianM.Scott what would you say is the subtractive notation of my example though?2012-05-23
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    There isn’t one: the subtractive notation is used only when an amount written with a single letter is being subtracted. One doesn’t write IIV, meaning $5-2$, for $3$, and similarly, one doesn’t write XXXIIV, XXLIII, or XXLIIV, meaning $30+5-2,50-20+3$, and $50-20+5-2$, for $33$.2012-05-23
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    I see thanks alot :)2012-05-23
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    In fact, `IIII` was used for 4; some clocks still use it. As I heard it, Julius Caesar objected and introduced the reform of writing it as `IV` because `IIII` looked too similar to the beginning of `IULIUS`.2012-05-23
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    Just as an example for subtractive notation, 1999 is not generally written "IM", as might be supposed, but rather "MCMXCIX".2012-07-02
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    See http://groups.google.com/group/sci.math/browse_thread/thread/590a24a7df8a670f2012-07-02

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