In today's terms: MMCDLXXXVI
In today's notation of Roman numerals: MMCDLXXXVI but the Romans themselves would have probably chosen MMCCCCLXXXVI
Roman numerals are a system for writing numbers, not words. the Roman numeral for 4 is IV.
XCVIII is 98 in Roman numerals
Roman numerals for 201 = CCI
1008 in Roman numberals is MVIII
XXX1X
XLII
Iii.xiv
XC
DCCCII
DCC
MCMLXXXIX