Roman numerals and Greek alphabet

Roman numerals up to 10

Roman numerals

This numeric system originated in ancient Rome. Numbers in this 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

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:
A symbol placed after another of equal or greater value adds its value:
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=1000+500+100+10+10+1=1621

A symbol placed before one of greater value subtracts its value:
IV = V − I = 5 − 1 = 4
XC = C − X = 100 − 10 =90

No digit is repeated in succession more than thrice. The digits I, X and C can be repeated up to three times in succession to form the numbers. V, L and D are not repeated at all.

How to form a Roman numeral:
To convert a number to a Roman numeral write the numbers in expanded form and then replace the terms with correct symbols:
1511=1000+500+10+1=M+D+X+I=MDXI
969=900+60+9=CM+LX+IX=CMLXIX

Roman numerals 10-20

Roman numerals

This numeric system originated in ancient Rome. Numbers in this 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

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:
A symbol placed after another of equal or greater value adds its value:
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=1000+500+100+10+10+1=1621

A symbol placed before one of greater value subtracts its value:
IV = V − I = 5 − 1 = 4
XC = C − X = 100 − 10 =90

No digit is repeated in succession more than thrice. The digits I, X and C can be repeated up to three times in succession to form the numbers. V, L and D are not repeated at all.

How to form a Roman numeral:
To convert a number to a Roman numeral write the numbers in expanded form and then replace the terms with correct symbols:
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 this 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

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:
A symbol placed after another of equal or greater value adds its value:
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=1000+500+100+10+10+1=1621

A symbol placed before one of greater value subtracts its value:
IV = V − I = 5 − 1 = 4
XC = C − X = 100 − 10 =90

No digit is repeated in succession more than thrice. The digits I, X and C can be repeated up to three times in succession to form the numbers. V, L and D are not repeated at all.

How to form a Roman numeral:
To convert a number to a Roman numeral write the numbers in expanded form and then replace the terms with correct symbols:
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 Lowercase Name Currentequivalent 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.