The number 39 written as a roman numeral is XXXIX.
XXX1X
CCCLXXVIII
DCXLI
MMX
MCMLXXVII
IX
Letters are not numbers. Not all letters in the alphabet represent Roman numerals though some letters do.
In today's terms: XXXIX
3210 = MMMCCX in Roman numerals which are expressed in letters
The roman numeric way to write 46 is XLVI.
It is: 900 = CM