Q&A for How to Learn Roman Numerals

As shown above, use M with a bar (horizontal line) above it. That means 1,000 multiplied by 1,000. Another way is to write M x M.

1) Memorize the meaning of the letters (e.g. M = 1000, C =100). 2) Learn to group the combinations in different digits (E.g. Thousandth, hundereded, tenth, ones; MMCMLXXVII = MM CM LXXX VII). 3) learn when to add and when to subtract. MMCMLXXVII = (1000+1000)+(1000-100)+(50+10+10+10)+(5+1+1) = 2987

Use flash cards, or read this article (or others like it) over and over again until it's committed to memory. There are no shortcuts. You just have to memorize.

According to the information above, when a smaller number is to the left of a larger number, you subtract the smaller from the larger. When the smaller number is to the right of the larger number, you add the two. This makes sense, if you think of it in terms the left=less than, and right=more than [like the larger number, plus moving forward (smaller number to right) is in addition to the larger number)]. It is like Arabic numeral system of "10's" (most widely used in the world today), where if you count backwards (similar to left) you are taking away or subtracting, and if you count forward (like to the right), you are increasing in value or adding.

5000 in Roman numerals would be V with a horizontal line on top. The horizontal line means to multiply by a thousand, so that would be 5 times 1000.

No, it's written as CDXCIX. When subtracting one value from another (as in the case of ID), the rule is that you can't subtract a number whose value is less than ten percent of the number to its right. Thus, because the value of I is less than ten percent of the value of D, I can't be subtracted from D.

The letters were not "picked." There is a long and convoluted history behind them. See the Wikipedia article "Roman Numerals."

Roman numerals are often seen in real life (on clocks, in math problems, in dates, etc.), so it's important that people know how to read them.

The repetition rule refers only to consecutive use. Four X's are all right if they aren't consecutive.

A pico-second is one-trillionth of a second. A time unit of even shorter duration is called a "Planck time," which is so short it's very difficult even to define or measure.

No. The Roman system was not well designed for mathematical use. The Romans developed a pebble-based accounting system (similar to an abacus) to help with their math solutions, because using the letter-based system was cumbersome and frustrating.

It may vary with location, but typically Roman numerals are taught in Year 4 / third grade.

You can use this mnemonic to memorize the order of the symbols used in Roman numerals (in descending order): My Dear Cat Loves Xtra Vitamins Intensely.

XCIII can be broken down into XC and III. XC is equal to 90, and III is equal to 3. When combined, it forms XCIII, which is equal to 93.

It is 467.

4325 is MMMMCCCXXV.

You can remember the mnemonic shown above. A lot of practice with these numerals is helpful too!

Addition or subtraction in Roman numerals system basically follows the same rules as in other number systems. The basis of addition or subtraction is basically on the values. So you are either adding (increasing) the value of a number (represent in any number system) or subtracting (decreasing) the value of it. In this case IV (4) - II (2) is II (2).

Writing in roman numerals is almost like writing in code or hieroglyphics, so use it as an opportunity to make math fun and engaging. While learning to read and write Roman numerals might not be the most important math your child will learn, I believe there is still value in it.

M is 1000 and D is 500, that will be 2x1000 is 2000 and I is 1, so that would be 2000.

No, the XX is correct. But the VXI is incorrect. I see what you did, XI would be 9 and if you put a V in front of it, it would be 4. But you can't do that. You would write 24 as XXIV.

You could write it as an IX with a line over it, then CMXCIX IX with a line over it is 9000, and CMXCIX is 999 and 9000+999=9999.

The clocks you've seen that on are probably Roman clocks. In Roman numerals, I means one, so IIII means four.

In Roman numerals, when a smaller number precedes a larger number, that indicates subtraction. CD means that 100 is being subtracted from 500, and CM means that 100 is being subtracted from 1,000.