You'll need more food and water than you think.

[Gizmo]

Like has been mentioned the exersize seems a bit pointless but the actual topic is one that quite a few people seem to have problems with. Often people seem to underestimate their families food requirements or over estimate how much actual food they have in stock. To my way of thinking the simplest way of gauging how much you have is to count the calories of what you have and divide it by days and people, quite a few people just seem to look in their cupboards and say, yup, 3/6/9 months there, without actually working it out properly.

Just in case anyone thinks I am being harsh or bitching, i'm not. I did exactly the same when I first started storing food. I was quite confident I had at least 3 months food for my family, when I worked it out properly I had less than 1 month. And although not many people will ever admit to doing the same, I know for certain that at least 2 people I have met up with did do the same.