Roman Numerals

Roman Numerals was a system that was the way that the Roman’s would write different numbers.

Instead of using numbers that we use today, the Romans would use letters such as I, V, L, C, D, and M.  All of these numbers would work together in order to make a whole number.

Roman Numerals

Each letter above represents a set of numbers including:

• I which represented the number 1
• V which represented the number 5
• X which represented the number 10
• L which represented the number 50
• C which represented the number 100
• D which represented the number 500
• M which represented the number 1000

All of the letters can be used in order to add value and to make numbers work together.  There are different rules like the math rules that we use today that the Ancient Romans also had to use.

Addition of Roman Numerals

In order to add Roman numerals, you had to follow this rule:  If the larger number letter is on the left-hand side, you add the number letters together to equal the total.

Subtraction of Roman Numerals

In order to subtract Roman numerals, you had to follow this rule:  If the larger number letter is on the right-hand side, you will subtract the number letters together to equal the total.

Examples of Adding and Subtracting Roman Numerals:

• I equals 1
• II equals 2
• III equals 3
• IV equals 4
• V equals 5
• VI equals 6
• VII equals 7
• VIII equals 8
• IX equals 9
• X equals 10
• XI equals 11
• XII equals 12
• XIII equals 13

In order to get 12, you would take X that equals 10 and ad I which equals 1 and another I which equals 1 making the total XII.

Roman Numeral Rules

There are different rules when working with Roman numerals including:

1. You cannot put more than three letters in one row.
2. When you want to subtract a letter, you put the lower value before the higher one.
3. You can only subtract one number.
4. The smaller number or letter must be at least 1/5^th or 1/10^th of the larger number.
5. If you put a bar over a number, you can multiply it by 1,000 so that it makes a huge number.

Counting By Ten

If you want to count by ten, the Roman numerals look like this:

• X
• XX
• XXX
• XL
• L
• LX
• LXX
• LXXX
• XC
• C

That was 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 in Roman numerals.

Facts About Ancient Roman Numerals

• Many clocks have Roman numerals on them.
• Kings and Queens are named after Roman numerals such as Henry VII.
• There are no zeros in Roman numerals.
• The Romans also used fractions which were called uncia.
• Roman numerals are sometimes written to write the years.
• The Romans would sometimes use Roman numerals as the days of the week.

What Did You Learn?

1. What are Roman numerals?  Roman numerals are letters that the Romans used to count.
2. Can Roman numerals be added and subtracted? Yes, Roman numerals can be added and subtracted and even multiplied.
3. Do the Roman numerals have rules? Yes, there are many rules when using Roman numerals.
4. What can be put over a Roman numeral in order to make it a large number? The letter can have a bar over it to make it a very large number.
5. What are some uses of the Roman numerals? Roman numerals are used to count, they are used to name kings and queens and they are used to write the dates of things.