Update romannumbers.en.md

subjects/romannumbers.en.md

@@ -2,9 +2,33 @@
 
 ### Instructions
 
-Write a program called `rn`. The objective is to converte a number, given has argument, into a roman number and print it with roman number calculation.
+Write a program called `rn`. The objective is to convert a number, given as an argument, into a roman number and print it with its roman number calculation.
 
-The program should have a limit of `4000`. In case of an invalid number, for example `"hello"` or  `0` the program should print `ERROR: can not convert to roman digit`.
+The program should have a limit of `4000`. In case of an invalid number, for example `"hello"` or  `0` the program should print `ERROR: can not convert to roman number`.
+
+Roman Numerals reminder:
+I -> 1
+V -> 5
+X -> 10
+L -> 50
+C -> 100
+D -> 500
+M -> 1000
+
+For example, the number 1732 would be denoted MDCCXXXII in Roman numerals. However, Roman numerals are not a purely additive number system. In particular, instead of using four symbols to represent a 4, 40, 9, 90, etc. (i.e., IIII, XXXX, VIIII, LXXXX, etc.), such numbers are instead denoted by preceding the symbol for 5, 50, 10, 100, etc., with a symbol indicating subtraction. For example, 4 is denoted IV, 9 as IX, 40 as XL, etc.
+
+The following table gives the Roman numerals for the first few positive integers. 
+
+1	 I	  11 XI	   21	XXI
+2	 II	  12 XII	 22	XXII
+3	 III	13 XIII	 23	XXIII
+4	 IV	  14 XIV	 24	XXIV
+5	 V	  15 XV	   25	XXV
+6	 VI	  16 XVI	 26	XXVI
+7	 VII	17 XVII	 27	XXVII
+8	 VIII	18 XVIII 28	XXVIII
+9	 IX	  19 XIX	 29	XXIX
+10 X	  20 XX	   30	XXX
 
 ## Usage
 
@@ -22,6 +46,6 @@ student@ubuntu:~/[[ROOT]]/test$ ./rn 3999
 M+M+M+(M-C)+(C-X)+(X-I)
 MMMCMXCIX
 student@ubuntu:~/[[ROOT]]/test$ ./rn 4000
-ERROR: can not convert to roman digit
+ERROR: can not convert to roman number
 student@ubuntu:~/[[ROOT]]/test$
 ```