[O] using a simple numerical variable in an org text ocument

[Matt Price]

Hi,

I'm making a very simple org-document -- a packing list for a trip.
It has entries like

- 4 mugs
- for sleeping bags
- 4 thermarest pads


I'd like to replace the numbers there by a variable -- so if I make a
list for 4 people, the number displayed will be '4'; but if the list
is for 2 people, the number displayed will be 2.  Better would be if I
could also do simple arithmetic manipulations (x * 6 dinners for a
week...).  I there a really simple way to do this? if it's not really
easy, it won't really seem worth it, but if it is really easy, I will
use it a lot...

Thanks guys!
Matt