What is this roman numerals xix?

Answer 1

X=10 and I=1

IX=9 because I<X and I comes before X therefore IX= 10-1

XIX= 10 + 9 =19

OR It can be done by the following method:

Write the numerical value of each roman number.

e.g. 10,1,10 These numbers should be in descending order i.e. first number should be the largest, second should be less than or equal to first and so on. In XIX, numerical values are 10,1,10 clearly 10 at the third place does not follow the sequence so number at 2nd place will be subtracted from the sum i.e. 10+(-1)+10=19

Take another example of DCXLIX. Write the numerical value of each roman number.

500,100,10,50,1,10. Clearly 50 at 4th place and 10 at 6th place do not follow the sequence. So, 10 + 1=11 will be subtracted from the sum i.e.

500+100+(-10)+50+(-1)+10=649