Virus free and backed up for another week

Me weekly virus scan has just finished, fortunately my likkle laptop is virus free again, so I backed everything up same as I do every Saturday.

GCSE maths question for you though: if a number is recurring, do you write it as the number that recurrs a couple of times then a little r floating above the last recurring number?

The reason for the question is that I was trying to work out how long it'd take to finish the first of the 3 sections.  I knew that 1% took 20 seconds and I had 37% left to do so Steve used his calculator to work out that it was seven hundred and something seconds which was 12.333333333333333 recurring minutes so I asked him how that was written if you wanted to save space instead of filling it up with endless 3's.

I thought it was written as 12.3ͬ minutes... is that right please?  I don't want a whole maths lesson on it 'cos my eyes would glaze over before you finished the first sentence and it'd go in one ear and straight out the other without even pausing in my brain, just like it did at school.  I just wanna know if the r thingie really is a maths thing to symbolise recurring or if it's my imagination is all.

Feel free to laugh at my dumbo question now  lol