Collecting milk lids = a math lesson

With help from the other soy milk drinkers in the family, we'd been collecting the Red Dress foil lids from 8th Continent Soymilk. The baggie was getting full, and in our Advent cleanup mode, it was time to get these lids on their way.

But, before sending them in, we wanted to know how much money 8th Continent would donate to women's heart disease awareness as a result of our efforts.

Well, said S, each one is worth 50 cents, so two are one dollar. He then made piles of two... for a total of 24 piles. Wow! We had $24!

Then, we wanted to know how many lids we had:

2 lids/pile x 20 piles = 40 lids.
2 lids/pile x 4 piles = 8 lids.
40 lids + 8 lids = 48 lids!

There was one more challenge: figuring out the combination of stamps needed to send the envelope on its way. That, too, accomplished, the intrepid lid counter set off to the post office...