Transcript File

Roman Numerals
I (1) – XII (12)
2nd Grade – Robin Daugherty
Objective: Students gain knowledge of the
history of Roman Numerals and how to
translate Roman Numerals I – XII to Arabic
Numerals.
Roman Numerals
What are Roman
Numerals?
•Romans did not use numbers like we
use…They used letters to represent their
numbers.
The Romans used a combination 7 letters to
make all of their numbers!
We use what is call Arabic numbers. We use
the numbers 0-9 to make all of our numbers.
•
•
What is a Roman Numeral?
•The Following are the Roman Numerals that we are going
to learn today:
I-1
V–5
X - 10
•For our number one, the Romans used a capital I.
•For our number five, the Romans used a capital V.
•For our number 10, the Romans used a capital X.
History of Roman Numerals
•The symbol "I" for 1 was
derived from one finger.
Five fingers held up
indicated five of whatever
was being counted.
The "V" then was the
hand outstretched vertically
with the space between the
thumb and first finger
forming the "V".
•
History of Roman Numerals
•Another theory for "X" is
that ten 1's were written in
a row, and then crossed out
with an "X" to simplify
counting.
History of Roman Numerals
Then the "X" alone became
a shorthand version of 10.
Yet another idea is that "V"
looks like the top half of "X",
as 5 is half of 10, and other
scholars think that "V"
doubled with an upsidedown "V" meant 5 times 2,
or "X".
Rules for Roman Numerals
There are 3 basic rules for
using and counting with
Roman Numerals. We will
go through the rules oneby-one and give examples
for each rule.
First Rule
1. Add repeated
numerals.
I–1
II – 2
III - 3
Second Rule
2.Add when a lesser numeral
follows a greater one.
I=1
V=5
Which Numeral is
Greater the I or the V?
Second Rule Cont…
2.Add when a lesser numeral
follows a greater one.
For the Number VI, the I
is less than the V so we
add because we add when
a lesser numeral follows a
greater one. V + I = VI or
5+1=6.
Second Rule Cont…
2.Add when a lesser numeral
follows a greater one.
What is this number –
VII?
7 because V = 5 and I =
1. So 5+1+1=7
Second Rule Cont…
2.Add when a lesser numeral
follows a greater one.
What is this number –
VIII?
8 because V = 5 and I =
1. So 5+1+1+1=8
Third Rule
3. Subtract when a lesser
numeral comes before a
greater one.
I=1
V=5
Which Numeral is
lesser the I or the V?
Third Rule
3. Subtract when a lesser
numeral comes before a
greater one.
For the Roman
Numeral IV, the I is less
than the V, because I =
1 and V = 5. So, the
number is V-I=IV or
5-1=4
Third Rule
3. Subtract when a lesser
numeral comes before a
greater one.
What is IX? X = 10
and I = 1.
The Answer is 9
because X – I=IX
or 10-1=9.
Review of all Roman Numerals
I=1
II = 2
III = 3
IV = 4
V=5
VI = 6
VII= 7
VIII = 8
IX = 9
X = 10
XI = 11
XII = 12