I-1 USA

II-2 duet

III - 3 tres

IV-4 quatto or

Five to five years old

VI-6 gender

VII-7 septies

VIII-8 October

IX-9 1 1 month

X-10 October

XI-1 1 November

XII-12 December

XIII - 13 tresdecim

XIV - 14 quattuordecim

Decimal system

XVI - 16 sedecim

XVII-17 September 10th

XVIII - 18

XIX - 19

XX-20 viginti

XXI - 2 1 viginti unus

XXII - 22 viginti duo

28-28 Duodenal resection

Twenty-ninth sessiona

XXX - 30 triginta

XL - 40 quadraginta

L-50 quinqua gold pagoda

1~ 10: one two three four five six seven eight nine X.

1 1~20: XI XII XIII XIV XV XVI XVII XVII XVII XVII XIX XX

2 1~30: 21 22 23 25 27 28 29 30

3 1~40: XXXII XXXIII XXXIV XXXV XXXVI XXXVII XXXVIII XXXIX XL

4 1 ~ 50:XLI XLII XLIII XLIV XLV XLVI XLVII XLVII XLIX L

Where I am 1.

V is 5.

X is 10.

L is 50

Li, 5 1

Lu, 55 years old

LX，60

Sixty-five

LXX 70

LXXX，80

XC, 90 years old

XCIII，93

XCV，95

XCVIII，98

Integrated circuit, 99

c， 100

CC，200

CCC，300

CD，400

500 dollars

DC，600

DCC，700

DCCC，800

Centimeter, 900

m， 1000

MC， 1 100

MCD， 1400

MD， 1500

MDC， 1600

MDCLXVI， 1666

MDCCCLXXXVIII， 1888

MDCCCXCIX， 1899

MCM， 1900

MCMLXXVI， 1976

Michael XXXIV, 1984

MCMXC， 1990

Well, in 2000.