The last few times I went shopping for breakfast cereal, I tried to compare the prices of various cereals on a per-ounce or –gram basis. Tonight, one cereal I bought was $2.84, and the package said it weighed 13 ounces or 368 grams. Calculating the price per ounce seems to be much easier than calculating the per gram price. I was able to quickly see that it costs about 20 cents an ounce (quite a bit cheaper than most other cereals) by multiplying 13 x 2, and then adding a zero. I then decided to try to get the cost per gram, but decided not to even try to put 368 into 284.
After a similar experience shopping last week, I saw that 20 cents an ounce was roughly equal to 0.7 cents a gram. I’m not sure that I want to multiply the number of grams by 7, and then move the decimal. Another option I thought of was to take a tenth of the gram total, and then subtract it 3 times (from that total), to see if the price was at 0.7 cents a gram or lower. Still, it seemed like a lot more work. I know folks can say it’s just that I’ve just gotten used to imperial measurements, but it does seem a lot easier to me to use when shopping, that’s for sure. Now I know that if our country were officially metric only, the supermarkets would be posting the prices in metric terms on the labels on the shelves, but honestly I don’t like to use them because the writing is so small (even when they are given with imperial units). OK now—is this simply a math process that I’ve forgotten about, that will allow me to calculate as easily with grams? Or is this simply an area where working with imperial units is easier? I am well aware of the various advantages of the metric system…. is this just an example of no system being perfect?
