Roman Numerals

Past and Present

Romans used a number system for commerce

Initially began by using tally marks Still used today in different ways

Roman vs. Arabic Numerals

Arabic numbers are Used but not in standard for today

everyday math foundation is

1,2,3,4,5,6,7,8,9,0 the base ten I, V, X, L, C, D, M

system numbers can be no symbol for

zero repeated more than 3 times

The Basics of Roman Numerals

I = one (1)

V = five (5)

X = ten (10)

L = fifty (50)

C = one hundred (100)

D = five hundred (500)

M = one thousand (1,000)

Rules for Writing Roman Numerals

1) Letters should be arranged from largest to smallest

-1510 is written MDX, largest to smallest

2) Only powers of ten can be repeated. 3) Letters can not be repeated more

than 3 times in a row except for I-100 is written LL, not XXXXXXXXXX

Rules continued…….

4) Numbers can be written using subtraction with the first letter being smaller than the letter that follows (the smaller number is written to the left of the larger number)

Example:-Nine (9) is written as IX (1 taken away from 10 or 1-10/10-1)

-nine hundred and ninety is written as (10 taken away from 1,000) + (100-10)

XM + XC = XMXC

-249 is written as 100+100+ (50-10) + (10-1) = C C XL

IX CCXLIX

- How would you write 40, 92, 499?

When in Rome, do as the Romans do!!

Abide by the customs of a society when one is a visitor.

Practice Number Conversions

I = one (1)

V = five (5)

X = ten (10)

L = fifty (50)

C = one hundred (100)

D = five hundred (500)

M = one thousand (1,000)

Practice515 = ?

1005 = ?

32 = ?

*993 = ?

*19 = ?

Answers515 = DXV

1005 = MV

32 = XXXII

*993 = (1000-10) + (100-10) + 3 XM XC III = XMXCIII

*19 = 10 + (10-1) X IX = XIX

Adding the Roman Way

Add

23 + 58 =

show all your work using

Roman Numerals

Standard Number

Roman Numeral

1 I

5 V

10 X

50 L

100 C

500 D

1000 M

Adding the Roman WayHow did they do that?

Step 1. 23 + 58

Sept 2. XXIII + LVIII

Sept 3. XXIIILVII

Sept 4. LXXVIIIIII

Sept 5. LXXVVI

Sept 6. LXXXI

Sept 7. 23 + 58 = LXXXI

Adding the Roman Way

77+ 32 =

345+60 =

CCLVI + LXXXII =

**LVI + XIX =

Answer

77+ 32 = CIX

CCLVI + LXXXII = CCCXXXVIII

LVI + XIX = LXXV

Congratulations!!Independent Practice Time