Roman Numerals Medical Math in HealthScience Care Two

Roman Numerals Medical Math in Health/Science Care

Two Types of numbers § Arabic 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

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.

Continued…… § That means that 99 could be represented as XCIX - 90+9 but never as IC. § XC = 10 subtracted from 100 = 90 § IX = 1 subtracted from 10 = 9 § 90 + 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 900 + 9 = 999

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

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

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

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.

Forming Numerals § Numbers are formed by stringing the letters together to add up to the number required. § Examples – II = 2 – XXX = 30 – XII = 12 – CXXIII = 123 (1+1=2) (10+10+10 = 30) (10+1+1= 12) (100+10+10+1+1+1=123)

Examples of the official rules for subtracting letters: 1. Subtract only powers of ten, such as I, X, or C. Writing VL for 45 is not allowed: write XLV instead. 2. Subtract only a single letter from a single numeral. Write VIII for 8, not IIX; 19 is XIX, not IXX. 3. 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.

Time to test your knowledge Write the Roman Numeral § § § § 1 5 10 50 100 500 1000

Write the Roman Numeral § 19 § 724 § 2008 § 29 § 3916 § 200 § 1549 § 33 § 64 § 113

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

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 !