Numbers — they’re all around us. Can you imagine trying to get through your day without numbers? How would you know what time it is? How would your teacher know if everyone in your class is present?
When you first learn to tell time, one of the things that can be confusing is a clock that has letters instead of numbers on it. What’s up with that? Wouldn’t it be easier if all clocks were digital? And what do those letters mean anyway?
The letters on those clocks are actually numbers! Well…sort of. We call them Roman numerals. Instead of using numbers like we’re familiar with (1, 2, 3, etc.) — which are called Arabic numerals — the ancient Romans developed a numeric system which uses letters of the alphabet.
Here is the basic set of Roman numerals and what they represent:
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000
The rules for Roman numerals are a bit different than the rules for Arabic numbers. For example, Roman numerals don’t have a place value like Arabic numerals do. If you put a “1” after a “5” using Arabic numerals, you have “51.”
Using Roman numerals, though, “51” isn’t represented by an “I” after a “V.” Instead, it’s represented by LI (L = 50 + I = 1). This is because Roman numerals use an additive (or subtractive) system to add or subtract value from the basic Roman numerals listed above.
Here are the basic rules you need to know to read and write with Roman numerals:
- A letter repeats its value as many times as it’s used, but it can only be repeated three times. For example, XXX = 30.
- If one or more letters come after a letter of greater value, their values are added. For example, VII = 7 (5 + 1 + 1).
- If a letter comes before a letter of greater value, its value is subtracted. For example, IX = 9 (10 – 1 = 9). This rule has a few conditions: only subtract powers of 10 (I, X or C — not V or L); only subtract one number from another; and don’t subtract a number from another number that’s more than 10 times greater.
- A letter with a bar over it has a value 1,000 times greater than usual. For example, V = 5, but V with a bar over it= 5,000.
In addition to certain clocks, you’ll also often see Roman numerals used in the credits of movies to indicate the year of release. For example, if you go to the theater to see a new movie in 2012, you may see the letters MMXII instead of the Arabic numerals 2012.
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This is really interesting and just a little confusing. But great wonder! Today I’m going to pay attention to how many times I actually use numbers.
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We’re glad you’re here today, Savannah! Thanks for WONDERing with us! We bet you’ll be surprised how many times you use numbers today– what a great way to continue WONDERing!
I thought it was going to be Roman numerals but I didn’t know that it would be can you count by letter. That really inspired me and oh I forgot I’m in the PinkPanthers class.
Way to go, Tigerlover, you correctly guessed today’s Wonder of the Day®! We’re glad you and your Wonder Classmates have been visiting us- it’s great to see you! We bet you’ll see some Roman numerals if you watch the Super Bowl tomorrow!
Counting with letters. AMAZING. Love it.
Hey there, Wonder Friend Shimoly! Thanks for sharing your comment today! We’re glad you liked our Roman numeral Wonder– have a great day, filled with counting!
Hi Wonderopolis. My dad has a clock like that. First it was hard. I thought that was it but there was more. I learn a lot. Thank you. I think it will be the a,b,c.
Sometimes clocks with Roman numerals can take a while to read, Kittyqueen! But with some practice, we bet you got the hang of it! Thanks for sharing your comment and WONDERing with us today! See you soon!
Hi wonderopolis!! I loved today’s wonder!!! My class is going on wonderopolis every day now!! I wonder what tomorrow’s wonder will be!!!
We’re so glad you and your Wonder Classmates have been visiting us everyday– how lucky are we?! Thanks for sharing your awesome comment today, Holly- we’re glad you liked today’s Wonder!
Hi wonderopolis!!! I have a clock just like the one in the picture. I wonder what tomorrow’s wonder will be!!!
How cool, Holly! You can practice your Roman numeral knowledge on that awesome clock! See you tomorrow, Wonder Friend!
I don’t get Roman numerals.
Hey there, Aidan, you’re not alone! Roman numerals can be tough to learn at first, but with some practice, you’ll be a counting wizard! Take a look at the excerpt below for more information:
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000
I really don’t understand Roman numbers do you?
Hey there, Wonder Friend Valerie, not to worry, Roman numerals can be tough to get at first! However, we bet you will be a Roman numeral expert with some practice and time! We’ve listed the first steps to understanding Roman numerals below:
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000
Check out the Roman numerals used in tomorrow’s Super Bowl game!
My family has a giant roman clock in the living room! I knew this was the wonder today. By the way did you know you are our homework and morning work too?! Our teacher, Mrs. Hess, loved you so much! We talk about you all the time!!
How cool, Ky Duyen Quang! We’re so glad you can relate to our Wonder today! We think it’s awesome that you and your Wonder Classmates from Mrs. Hess’ room join us every day! We’re so lucky to have great Wonder Friends like you! Thanks for visiting us today!
I think tomorrow’s wonder will be letters that they used in the olden days.
Your wonder friend
cailyn d
Nice work, Cailyn D! We’re so glad you shared your Wonder guess with us today! We think you’re a great Wonder Friend!
Hey there are Roman numerals in Star Wars video game well the Lego one I only knew these.
Great connection to today’s Wonder, doglover! You’ll notice more Roman numerals in the future now that you’ve WONDERed about them!
I used to think that Roman numerals were extremely confusing, but now they make perfect sense! I also used to think that 9 was IVV. In math class, we just started working with Roman numerals, so this wonder is VERY helpful.
I think that tomorrow’s wonder will be about vowels and consonants.
We’re so glad you learned something new with us today, Christine! Roman numerals are tough to get in the beginning, but we’re glad today’s Wonder helped clear things up!
I can’t watch the Super Bowl I like football but sometimes I get tired and turn it off. I’m sorry.
Not to worry, Valerie! Some big games are so long that you have to take a break, or watch only a little bit. We’re sure glad you’re WONDERing with us today!
I thought that today’s wonder was fascinating. I never really understood Roman numerals above 10, but now they are coming to me really easily. In class on Friday we learned about Roman Numerals but only from 1 to 10, or should I say I to X.
Thanks for sharing all you learned, Colin! Roman numerals are tough to get in the beginning, but you’ll be a pro in no time! See you tomorrow, WOnder Friend Colin!
Hi Wonderopolis, I actually saw this in the commercials for the Superbowl. In school we need to know the Roman numerals for I II III and IV. My father showed me once the Roman numerals for a DVD of a movie. They do that because they don’t want people to easily find out when the movie was made. It is really cool how you come up with questions that not many people think about.
We’re so happy that you and your father have been WONDERing together today, minecrafter! We hope you have a SUPER day full of WONDERing… and maybe you’ll even watch the Super Bowl, too!
I love Roman Numerals and I love comparing other number systems. It makes learning about Numeracy that little bit richer!! Great wonder!
That’s great news, Bridget! We’re so glad you’re enjoying today’s number Wonder! HOORAY for learning!
Hello ! just wanted to let you know that there is an eror on the information page where you describe the use of the ‘bar over a letter’
the V=5 printed ok, but there is no ‘V bar’only the ‘=5000′ printed.
Thanks so much for pointing that out, Pam! We’ve got you covered, and we’ve corrected that mistake! We appreciate your comment and your help for our Wonder community!
Wow I can’t believe I was right about today’s wonder.
Nice work, tigerlover! Way to go!
I think that a lot of people have a lot of trouble backward without looking on the abc line it is very interesting. I wonder what is next.
Thank you so much for WONDERing about letters and numbers with us, Leticia! We’re glad you visited our Wonder of the Day® and learned something new! See you tomorrow!
Hi wonderopolis! I love Roman numerals. I think they are fascinating. I can only count up to 10 in Roman numerals. I think I can translate 2013 into Roman nurmerals MMXIII.
There is a special pattern to figuring out Roman numerals if the smaller number is on the left then you would subtract that number from the number on the right. If the bigger number is on the left then you would add that number to the number on the left.
Nice work, John, you’ve got it right! 2013 is MMXIII in Roman numerals!
Thanks for sharing all that you learned from our number Wonder– you did a great job!
I never knew about Roman numerals. I think that they are a mystery to solve. I wonder how the people that invented the Roman numerals figured out how to do this I also wonder how people count by Roman numerals.
I really like leaving comments! Bye!
We like your style, Kathleen, Roman numerals are kind of like solving a mystery… until you know how to read them! Thanks for sharing your comments– we LOVE reading and responding to them!
Hi. My name was snowman. I studied Roman numerals in my school. I was wondering 9 in Roman numerals it VIIII until then. I learned Wonder, I found that it is IX.
Hey there, Snowman! We’re glad you’re here today! We’re glad you learned something new with us– you’ve got your Roman numerals down! NICE WORK!
Hi wonderopolis I am from Mrs.Caplin’s class and we are learning about Roman Numerals. The first time I saw Roman Numerals I thought they where just mixed up letters. The video was helpful because it helped me learn the bigger numbers.
Hey there, Cade768- welcome back! We’re so glad you understand Roman numerals– it’s like learning a new language! We hope you’re having a great day, Wonder Friend!
Hey that was great you guys are awesome and keep up the good work!
Well thanks so much, Faith! We’re glad to have a super Wonder Friend like you!
Hello Wonderopolis, I am in Mrs. Caplin’s class. I thought today’s wonder was awesome! I have a Roman numeral clock in my house so this can help me understand it better. I did not know that are numbers are Arabic numerals. One of the wonder words was value. In 6th grade math my first topic was place values. I think tomorrow’s wonder will be about different languages.
Thanks for WONDERing with us, Simba! We are so glad you can relate to our number Wonder– we bet you’re becoming a Roman numeral expert! Thanks for sharing what you learned and what you think the next Wonder will be– we can’t wait! AHOY!
Hi, I’m Maddy from Mrs. Caplin’s class. The video was very funny because it was obvious you don’t have to know Roman Numerals to play in the NFL. I really didn’t understand Roman Numerals until a few days ago. I only knew I, II, III. But this Wonder really helped me. What is a million in Roman Numerals? I liked this Wonder a lot.
Hey there, Maddy11! Thanks for sharing what you learned about Roman numerals– and how they are part of the Super Bowl! You’re right- you don’t have to know how to read Roman numerals to play in the NFL, but it’s cool to know how many Super Bowls there are if you can read them! To answer your question, we have to explain: One million in Roman numerals is M with a bar over it. M = 1,0000, and when you put a line, or a bar, over the letter, it multiplies it by 1,000. 1,000 x 1,000 = 1,000,000.
I think writing in letters may affect how people read letters. Human eyesight is very precious so we must keep it safe. It might make us more comfortable reading China numerals.
Hey there, Jacob, we are glad you’ve been thinking about how important our eyes are! Wonder #113 is right up your alley:
Why Do Some People Need Glasses? http://wonderopolis.org/wonder/why-do-some-people-need-glasses/
We Wonder if you can tell us more about the Chinese numerals you are WONDERing about! We LOVE to learn new things– do you know how to read Chinese script?