Are there any differences between modern and ancient notation of Roman numerals and if so could you kindly explain what they are please?

Answer 1

Yes there are some differences between modern and ancient usage of Roman numerals and the following gives a very brief explanation:

Modern:

Units from 1 to 9: I, II, III, IV, V, VI, VII, VIII, IX

Tens from 10 to 90: X, XX, XXX, XL, L, LX, LXX, LXXX, XC and 100 = C

To select a number write out the tens first then followed by the units.

Examples: XV = 15, 49 = XLIX, 99 = XCIX

Ancient:

Units from 1 to 9: I, II, III, IIII, V, VI, VII, VIII, VIIII

Tens from 10 to 90: X, XX, XXX, XXXX, L, LX, LXX, LXXX, LXXXX and 100 = C

To select a number do the same as the above, first the tens followed by the units.

Examples: XV = 15, 49 = XXXXVIIII then simplified to IL, 99 = LXXXXVIIII then simplified to IC

There is strong evidence that exist today that thoroughly supports the fact that the latter mode of writing out Roman numerals was used by the Romans themselves rather than the former mode.