1. Medical Math in Health/Science Care
Roman Numerals
Medical Math in Health/Science Care

2. Two Types of numbers Arabic numbers Roman Numbers
The numbers we normally use
1,2,3,4,,,,,,,,
Roman Numbers
Invented by the romans and still used today
I, V, X, L, C, D, M

3. Hx of Roman numerals
Romans strictly represented units as separate items in their numbers.
the numerals represented numbers as they were depicted on an abacus - a calculating machine using pebbles or beads which were arranged from right to left in columns of units, tens, hundreds, thousands etc.

4. Continued……
That means that 99 could be represented as XCIX but never as IC.
XC = 10 subtracted from 100 = 90
IX = 1 subtracted from 10 = 9
= 99
999 cannot be IM
IM is not legal
999 = CMXCIX
CM = 100 from 1000=900, XC = 10 subtracted from 100 = 90 and IX = 1 subtracted from 10 = 9
Therefore = 999

5. Roman Numerals You must Learn
I = 1
V = 5
X = 10
L =50
C =100
D = 500
M = 1000

6. Roman Numeral Rules
You can’t add more than 3 of the same letters at one time.
Ex: 4 is IV not IIII
use the biggest numeral possible at each stage
Ex: 15 XV not VVV or XIIIII.
A smaller value letter to the left of a larger value one is subtracted
Ex: 34 is XXXIV not XXXIIII

7. Three Subtraction Rules
Only I, X. and C can be subtracted
Only one smaller number can be placed to the left Ex: 9 = IX
The subtracted number must be no less than a tenth of the value of the number it is subtracted from.
I can only be subtracted from V & X
X can only be subtracted from L & C
C can only be subtracted from D & M

8. Three Subtraction Rules
These rules only became official in the Middle Ages. Even today, not everybody follows them.
Made to ensure compliance, set standards and provide guidance.
Made to be broken, some common examples of broken rules are on clocks, monuments and tombs.

9. Forming Numerals
Numbers are formed by stringing the letters together to add up to the number required.
Examples
II = (1+1=2)
XXX = ( = 30)
XII = (10+1+1= 12)
CXXIII = ( =123)

10. Examples of the official rules for subtracting letters:
Subtract only powers of ten, such as I, X, or C. Writing VL for 45 is not allowed: write XLV instead.
Subtract only a single letter from a single numeral. Write VIII for 8, not IIX; 19 is XIX, not IXX.
Don't subtract a letter from another letter more than ten times greater. This means that you can only subtract I from V or X, and X from L or C, so MIM is illegal.

11. Time to test your knowledge Write the Roman Numeral1 5 10 50
100
500
1000

12. Write the Roman Numeral19
724
2008 29
3916
200
1549 33 64
113

13. Write the Arabic # CCXXIV LXXXII DCCLXXV MCDXII MMMDDCDII MMIX
CXXXVIII
DXLIX
CMLXIII
XIV

14. Homework Create 10 roman numerals.
Each number must contain a minimum of 2 Roman numerals
Remember to follow your rules
You need to understand this, so please take it serious. Be able to explain your numbers to me.
This counts as a grade.
Good Luck !