How to write 491 in roman numberals?

Answer 1

XDI - D=500, X=10 and I=1... Placing the X before the D means you subtract it from the larger number, then add the 1. Another (longer) way to write it would be CCCLXXXIX (100+100+100+50+10+10+10+9)

Additional Information:-

In today's notation of Roman numerals 491 is: CDXCI

But the Romans themselves would have worked out 491 as CCCCLXXXXI and then simplified it to XDI (501-10 = 491) which uses less numerals but of equal value