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3.3.6: Roman Numerals

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Why study Roman Numerals?

Even though Roman Numerals are rare in today’s society, they are still used and expected to be understood. They are taught in grades three through five, depending on the district. They can be seen in clocks, the Super Bowl, Film Credits for the copyright date like MCMLXII, preface of textbooks and others like Star Wars Episode VI and WWII.

2.4.1: Basic Table of Roman Numerals
Value Symbol

1

I

5

V

10

X

50

L

100

C

500

D

1000

M

2.4.2: The Complete Table of Roman Numerals

1

2

3

4

5

6

7

8

9

ONES

I

II

III

IV

V

VI

VII

VIII

IX

TENS

X

XX

XXX

XL

L

LX

LXX

LXXX

XC

HUNDREDS

C

CC

CCC

CD

D

DC

DCC

DCCC

CM

THOUSANDS

M

MM

MMM

¯IV

¯V

¯VI

¯VII

¯VIII

¯IX

TEN THOUSANDS

ˉX

¯XX

¯XXX

¯XL

ˉL

¯LX

¯LXX

¯LXXX

¯XC

HUNDRED THOUSANDS

ˉC

¯CC

¯CCC

¯CD

ˉD

¯DC

¯DCC

¯DCCC

¯CM

Example 3.3.6.1

For all numbers except 4 and 9, we ADD the Roman Numerals together, in order from left to right, greatest value to lowest value.

11=10+1=XI8=5+1+1+1=VIII123=100+10+10+1+1+1=CXXIII3816=1000+1000+1000+500+100+100+100+10+5+1=MMMDCCCXVI7002=5000+1000+1000+1+1=¯VIIII

Example 3.3.6.2

For any number that includes a 4 or a 9, we subtract. When we are looking at a Roman Number expression and we see a Roman character OUT OF ORDER, which is the clue to SUBTRACT!

9=101=IX4=51=IV1400=1000+(500100)=MCD29452=10000+10000+100001000+(500100)+50+1+1=¯IXXXCDLII

Partner Activity 1

Convert Between Roman Numerals and Our Current Decimal System:

  1. MMXLV = ________
  2. MDCCLXXXIX = ________
  3. 1993 = ______
  4. 5495 = ______

Practice Problems

Convert Between Roman Numerals and Our Current Decimal System:

  1. 84759
  2. MMXX
  3. MCMLXXXII
  4. 1764
  5. 50000
  6. ¯XXLXXXIX

This page titled 3.3.6: Roman Numerals is shared under a not declared license and was authored, remixed, and/or curated by Amy Lagusker.

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