Thanks dnordstrom, very helpful.
But I seems I'm not done with it – need more assistance
Could you please have a look here: http://www.fightforsight.org.uk/carrots-regfee
Of course, the "Total to play" field doesn't update as it should. It only updates properly once the user enters something into the donation field (plus if the '0' isn't changed it displays "NaN").
How would I need to change the code for the Total field to update straight away, and so that a user can just tab through without haveing to overtype and change the '0' for donation?
Also, is there an easy way to make the first field "Number of participants..." a drop-down? Users should only really give a number from 1 to 6 here...
Sorry is I'm asking a lot here, and thanks for any help!