how to add new fields in post page?

[radiofranky]

hi,
i was wondering how to add additional input fields during thread posting which allow user to fill those input fields? then store into variables and could be used for example add the variable values to thread title

thread title + variables

variable 1 = 100 <= input by the user
variable 2 = 200 <= input by the user
and calculate variable 3 = 100/200 = 0.5 based on the inputs, calculate the third value

and in the final thread title will show something like this.
30 foot sail boat sale for $100, 50% off from it's original price

thanks