![]() ![]() For example, we can combine “XXXXX” into the symbol “L,” and we can combine “IIIIIIII” into the symbol “VIII.” This gives us MCCLLVVIII. Now all you have to do is combine symbols together wherever you can. The next step is to gather up and rewrite the symbols in order from largest to smallest. ![]() So the problem we’re now trying to solve is: MCLXXIIII + CXXXVIIII. Which means we need to rewrite “IV” as “IIII” and “IX” as “VIIII.” As it turns out-and as should be clear by the time we’re finished-the best thing to do is to rewrite these subtractive symbols using additive symbols (even if you have to violate the rule about having no more than 3 of the same symbol in a row). The only tricky part about adding Roman numerals is what you should do about subtractive symbols like “IV” and “IX” that have smaller numbers to the left of larger numbers. Let’s start by thinking about the example problem from before, MCLXXIV + CXXXIX. Like any good puzzle, it’s always best to try and solve it on your own instead of peeking at the answer. If you want to have some fun-of the puzzling type that I talked about at the outset-I encourage you to stop for a few minutes and try to come up with a method for adding Roman numerals. And that’s it! Once you know these rules, you know everything necessary to read and write Roman numerals.īut how in the world could you possibly do arithmetic with these numerals? It seems impossibly cumbersome and confusing to add Roman numerals like MCLXXIV + CXXXIX (aka 1,174 + 139), but it’s really not! You just have to think a little outside the decimal-system-lined box that we’re accustomed to living in. “I” is allowed to be subtracted from “V” and “X,” “X” is allowed to be subtracted from “L” and “C,” and “C” is allowed to be subtracted from “D” and “M,” but nothing else can be subtracted from anything else. For example, “IX” represents the number 10 – 1 = 9, and “CM” represents 1,000 – 100 = 900. If, on the other hand, a symbol representing a smaller value is written just before a symbol representing a larger value, we have to subtract the smaller value from the larger. Since each symbol represents a number that’s equal to or smaller in size than the number represented by the symbol to its immediate left, all of the values represented by the various symbols here are added together. In common usage, symbols are repeated no more than 3 times in a row.įor example, the number 1,272 is written MCCLXXII. If a symbol that represents a smaller number is written to the right of a symbol representing an equal or larger number, we add the values together. To write numbers other than these we combine various symbols together. ![]() ![]() In this system, the letter “I” represents 1, “V” represents 5, “X” represents 10, “L” represents 50, “C” represents 100, “D” represents 500, and “M” represents 1,000. So, with that in mind, let’s spend today having a bit of fun puzzling out how the Romans managed to do arithmetic.īefore we begin figuring out how to add and subtract Roman style, let’s recap how the Roman numeral system that we learned about last time works. But learning to see the many challenges you’ll face in life as puzzles that can be solved is a skill that will help you survive, thrive, and have fun. No, this isn’t a skill you need to survive in the modern world. Even though you may never need to use the math we talk about today, it’s still fun to puzzle out how ancient Romans could have added and subtracted their rather cryptic numerals. While those are fair questions, the truth is that math doesn’t always have to be serious and practical. For example, do you think today’s topic-adding and subtracting Roman numerals-sounds like fun? For many of you, the answer is “No!” And you may be wondering how this could possibly be useful? The key to this is approaching problems with the right attitude. And that certainly isn’t always tons of fun. And puzzles are fun, right? I realize that not all math problems are created equally-sometimes you have to use math to get real world work done. After all, math problems are really just puzzles. What’s 51 + 12? Easy, right? How about LI + XII? Not so easy…or is it? Keep on reading to learn all about adding and subtracting Roman style.ĭo you think math is fun? I absolutely think that it should be. ![]()
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