Question 418349
Roman numerals are very simple to use and add once you get a hang of how they work. Lets get a quick review: I is equal to 1. V is equal to 5. X is equal to 10. L is equal to 50. C is equal to 100. D is equal to 500 and finally, M is equal to 1000.

So if you were wanting to know all roman numerals from 10 to 40, just add it up.

X is 10. So to get to 11, just add one, right. Thats the symbol, I.
XI is 11. To represent adding put the symbol to the right of the initiator. And so follows the rest.
XII is 12.
XIII is 13.
XIV is 14. To represent a "4" in 14 we see it as 10 + 4, since the symbol for "4" is IV, and 10 + 4 = 14 so does X + IV = XIV.
XV is 15. We do the same thing here. Just add 10 (X) and 5 (V) together.
XVI is 16. From 6 and up we add on "I" as one to continue counting.
XVII is 17. 
XVIII is 18.
XIX is 19. Same thing as when we did 14. To say 19, add 10 + 9. And since 9 is represented as IX (you're taking 1 away from 10...9) its quite clear why we'd just put the two together. Remember when adding put the symbol in front of where you started. Just likewise, if you are subtracting put it before the initiator. (E.G. To say 9 we must do 10 - 1, or X - I or IX. When subtracting we only go down one digit. When adding we go up by 3 digits. You'll see this patter as I continue.
XX is 20.
XXI is 21.
XXII is 22.
XXIII is 23.
XXIV is 24.
XXV is 25.
XXVI is 26.
XXVII is 27.
XXVIII is 28.
XXIX is 29.
XXX is 30.
XXXI is 31.
XXXII is 32.
XXXIII is 33.
XXXIV is 34.
XXXV is 35.
XXXVI is 36.
XXXVII is 37.
XXXVIII is 38.
XXXIX is 39.
XL is 40. When we get to 40, its acts just like we were saying 4. Remember to say 4 we take V (5) minus I (1) or IV. So swap out V for L, (50) and to get 40 we subtract X (10) just like we would I (1). 50 - 10 is 40. L - X = 40 ( XL).
XLI is 41.
XLII is 42.
XLIII is 43.
XLIV is 44.
XLV is 45.
XLVI is 46.
XVLII is 47.
XVLIII is 48.
XLIX is 49.
L is 50. 

Hope this was helpful.