It's, I.
It is: 11 = XI as a Roman numeral
To write the number 9 in Roman numerals, you would use the symbol 'IX'. This is made by combining the Roman numeral for 1, 'I', and the Roman numeral for 10, 'X', subtracting 1 from 10.
E is not used as a symbol in the roman numeral system.
There is no Roman numeral represented by the symbol Y.
There is no specific symbol for Roman numeral fractions. The Romans did use fractions but they expressed them as a whole number followed by a fraction sign (usually "1/2", "1/4", or "1/8") placed after the whole number. For example, "II 1/2" would represent the number 2 and a half.
The Roman numeral V represents the number 5.
The symbol for 6 in Roman numeral is "VI".
A zero symbol
The Roman Numeral symbol for 500 is the letter D. You would represent the number 510 as DX.
C
C
XX