OKay, some random lecture...
We do not use the term "IL" in Roman Numeral counting. Although it would result into the same value, still it's wrong. 🙂
Using "IL" is also the same as using "XD", "VX", "DM", which are completely and definitely wrong.
The subtraction approach in counting Roman Numbers should be in this manner:
Since the symbols available in Roman Numbers are:
I V X L C D M
We do not subtract the symbol from "two-symbols away" another symbol.
Meaning, we cannot simply subtract "I" from "L", "V" from "C", or "L" from "M"... Rather, consider the possible "nearest" symbol.
Roman Numbers, in other way, is read literally from left to right, of course. So the exact sequence should be followed.
Consider the ff. illustration:
If we have 35, we use XXX + V ... counting up we'll be having:
XXXVI
XXXVII
XXXVIII ... since we're not using 4 similar symbols in counting, we use subtraction approach.
9 is found between the symbols V and X, but placing these two symbols together will reult into VX which denotes "10-5" and gives the result of "5". Unfortunately, 5 has it's own Roman Numerical symbol... so we simply use "V".
Now, we consider the preceding symbol, which is "I"... and we'll have "IX" which denotes "10-1" and results as "9"... and therefore the correct one.
In the case of number "49", we have "XL" as 40, and "IX" as 9... so, we can simply combine these symbols which represents 49...
Therefore, 49 is "XLIX". 🙂 Not "IL"...
In English, ... "IL" is a wrong GRAMMAR - Literally understood... but untolerable usage. 🙂
Back to counting:
MMDXLVIII - 2548
MMDXLIX - 2549
MMDXL - 2550
Now, we're on
2551
MMDLI 🙂