Hi, I am a school teacher and when we level pupils they receive a level and
then a sub level, which is unfortunately a letter, eg: 6C (being the lowest
of three sublevels in the 6s up to 6A being the highest, then onto 7C etc).

I have a level from last year, and want to compare that to their current end
of year level. I have beein saying that 6C is 62 and 6B is 65 and 6A is 68
but I find this confusing. I'd like to be able to say using some formula or
something that if they were 6C at the start of the year and are now a 6A,
then they have moved up 2 sublevels (+2 or something). Is there any way of
doing this without using my 62, 65, 68 solution????

Thanks.