We usually use the numerals 0,,1,2,3,4,5,6,7,8 ad 9 to
write numbers . These numerals are often called the Hindu-Arabic numerals
.Numbers are written using a place-value system in which the place value of a
digit gets multiplied by 10 as we move from right to left. For example , in 295
, the place value of the digits are : 5 X 1 = 5, 9 x 10 = 90 ND 2 x 100 = 200 .
The Romans used a different system . Their did not have any place value . They
had different rules for writing using seven letters .And they had no numeral
for 0.
90 is XC and not LXXXX ( more than 3 Xs together ).
80 is LXXX and not XXC ( you can subtract only once
from a numeral.
