if field value is greater or less than specific no then field value will be multiple of different no of a field in adobe acrobat form

Hi,

i have made a adobe acrobat form. here there r 3 fields - "d", "k" and "n" . if d>10 then k will be n.12, if d>15, then k will be n/6, if d>18, then k will be n/3. can ypu pls give me java sript for it?

thanks

Ali