[jQuery] calculate value of input based on two selects

[black.horizons]

hi guys,

just wondering how i would update the value of an input box to be the
value of the sum of two select (drop down boxes) plus 1.

i.e.

(select1.value * select2.value) + 1

I need to do this everytime either of the two fields are updated.

my pseudocode is:

select1.onUpdate{
   total.value = (select1.value * select2.value) + 1;
}
select2.onUpdate{
   total.value = (select1.value * select2.value) + 1;
}

if anyone can help me "translate" this to jquery i'd be mighty
relieved.

thanks,

alex