Roman numbers
Roman numerals are still used
occasionally. The BBC, for example, uses them to show the year
its
programmes were made in.
The Romans used letters for numbers.
I
is one.
To make two you put two
I
s
together:
II
To make three you put three
I
s together:
III
.
To stop the
numbers becoming very long they used other letters for some
larger numbers
and made the numbers between the letters by taking letters
away or adding
them.
V
is five.
To make four they put
I
in front of
V to indicate that the
one should be taken away from five:
IV
.
To make six they put
I
after
V
to
indicate that the one should be added to five:
VI
.
The Romans used
I
for one,
V
for 5,
X
for ten,
L
for 50,
C
for 100,
D
for
500 and
M
for a thousand.
The same principles of adding and taking away
letters are used throughout, so
MM
is 2,000,
MD
is 1,500,
XX
is 20,
XXIV
is 24.
If you have tried to understand the dates of BBC productions,
you will know
that most Roman numbers take time to decipher.
MCMXCVII
, for example, is
1997.
The
M
is 1,000,
to this is added
CM
for 900,
then
XC
for 90,
then
VII
for seven.
The difficulty gets much worse if you want to do arithmetic in
Roman
numerals. How, for example, do you work out how many years
before 2000 the
year 1997 was in Roman numerals?