Roman numerals and Greek alphabet

Roman numerals up to 10

Roman numerals

This numeric system originated in ancient Rome. Numbers in the Roman system are represented by combinations of letters from the Latin alphabet.

They are based on the following seven symbols, each with a fixed integer value:

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

The digits we normally use today, 0–9, are called Arabic numerals.

Basic numbers look like this:
1 - I
2 - II
3 - III
4 - IV
5 - V
6 - VI
7 - VII
8 - VIII
9 - IX
10 - X
15 - XV
20 - XX
40 - XL
50 - L
60 - LX
80 - LXXX
100 - C
200 - CC
300 - CCC
400 - CD
500 - D
700 - DCC
900 - CM

How to form a number

When symbols are written from a greater value to a smaller or equal value, their values are added:

Roman numeral

Decomposition

Result

II

I + I

1 + 1

2

III

I + I + I

1 + 1 + 1

3

LXXX

L + X + X + X

50 + 10 + 10 + 10

80

MDCXXI

M + D + C + X + X + I

1000 + 500 + 100 + 10 + 10 + 1

1621

In some cases, a smaller symbol placed before a larger symbol is subtracted. The standard combinations are IV, IX, XL, XC, CD and CM:

Roman numeral

Decomposition

Result

IV

V − I

5 − 1

4

XC

C − X

100 − 10

90

The symbols I, X, C and M can be repeated up to three times in succession. The symbols V, L and D are not repeated.

How to form a Roman numeral

To convert an Arabic numeral to a Roman numeral, write the number in expanded form and then replace each part with the correct Roman symbols:

Arabic numeral

Decomposition

Result

1511

1000 + 500 + 10 + 1

M + D + X + I

MDXI

969

900 + 60 + 9

CM + LX + IX

CMLXIX

Roman numerals up to 100

Roman numerals

This numeric system originated in ancient Rome. Numbers in the Roman system are represented by combinations of letters from the Latin alphabet.

They are based on the following seven symbols, each with a fixed integer value:

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

The digits we normally use today, 0–9, are called Arabic numerals.

Basic numbers look like this:
1 - I
2 - II
3 - III
4 - IV
5 - V
6 - VI
7 - VII
8 - VIII
9 - IX
10 - X
15 - XV
20 - XX
40 - XL
50 - L
60 - LX
80 - LXXX
100 - C
200 - CC
300 - CCC
400 - CD
500 - D
700 - DCC
900 - CM

How to form a number

When symbols are written from a greater value to a smaller or equal value, their values are added:

Roman numeral

Decomposition

Result

II

I + I

1 + 1

2

III

I + I + I

1 + 1 + 1

3

LXXX

L + X + X + X

50 + 10 + 10 + 10

80

MDCXXI

M + D + C + X + X + I

1000 + 500 + 100 + 10 + 10 + 1

1621

In some cases, a smaller symbol placed before a larger symbol is subtracted. The standard combinations are IV, IX, XL, XC, CD and CM:

Roman numeral

Decomposition

Result

IV

V − I

5 − 1

4

XC

C − X

100 − 10

90

The symbols I, X, C and M can be repeated up to three times in succession. The symbols V, L and D are not repeated.

How to form a Roman numeral

To convert an Arabic numeral to a Roman numeral, write the number in expanded form and then replace each part with the correct Roman symbols:

Arabic numeral

Decomposition

Result

1511

1000 + 500 + 10 + 1

M + D + X + I

MDXI

969

900 + 60 + 9

CM + LX + IX

CMLXIX

Greek alphabet

Greek Alphabet

One of the first alphabets in the world was used in ancient Greece. It was similar to our current alphabet. In addition to still being used in modern Greek, it has found application in mathematics.

The Greek letters, of which there are 24, have upper and lower case, just like ours. Each also phonetically represents one letter and at the same time has its own name.

Upper case	Lower case	Name	Current equivalent
Α	α	Alpha	a
Β	β	Beta	b
Γ	γ	Gamma	g
Δ	δ	Delta	d
Ε	ε	Epsilon	e
Ζ	ζ	Zeta	z
Η	η	Eta	h
Θ	θ	Theta	th
Ι	ι	Iota	i
Κ	κ	Kappa	k
Λ	λ	Lambda	l
Μ	μ	Mu	m
Ν	ν	Nu	n
Ξ	ξ	Xi	x
Ο	ο	Omicron	o
Π	π	Pi	p
Ρ	ρ	Rho	r
Σ	σ, ς	Sigma	s
Τ	τ	Tau	t
Υ	υ	Upsilon	u
Φ	φ	Phi	ph
Χ	χ	Chi	ch
Ψ	ψ	Psi	ps
Ω	ω	Omega	o

Knowing the symbol and name of each Greek letter is extremely useful in mathematics because they occur very often. Among other things, Greek letters denote angles in geometry, also one of the most important constants in mathematics is called π (pi). And the letter Δ (delta) is a generally accepted symbol for difference in mathematics. Greek letters are not only used in mathematic. The World Health Organization used letters of the Greek alphabet to name coronavirus variants: delta and omicron.