(That's the course that follows Unit Pricing 101, of course!)
Unit pricing (for the uninitiated) is the calculation that grocery stores put on the shelf price tags that tell you how much an item costs per pound, per ounce, per 100 count, etc. It's arrived at by dividing the price of the whole package by the amount of stuff in the package.
So, a pack of 200 red Solo Cups — because it's time to party! — that costs $2.99 would have a unit pricing of 1.5 cents each.
If only it were always that easy!
Unfortunately, not only do the units not match how the product is used, but sometimes the units used between different brands or sizes of products is different.
We ran across one unit pricing calculation that was a bit of a pain, actually: cedar shavings. We wanted to get some to put underneath our daughter's playhouse to try to cut down on the bugs in the area.
Cedar shavings, as we found out, aren't sold by weight, but by volume. Walmart had two package sizes: 500 cubic inches, and 5 cubic feet.
Quick quiz: Which is larger: 500 cubic inches, or 5 cubic feet? Would you know if the packages weren't in front of you?
If you didn't know that the 5-cubic-foot package is larger, I certainly wouldn't hold it against you. I could figure it out, but I'm an admitted math geek who actually likes numbers and stuff like that. The conversion is 1 cubic foot = 1,728 cubic inches: 12 inches times 12 inches times 12 inches.
There were a number of of the 500-cubic-inch packages left (with a price of $3.60), but only one of the 5-cubic-foot packages left for $7.80. We got the one big package, and decided against the little ones. The smaller packages had a much higher unit price.
Using rough numbers, the 500 cubic inch package is “about” 1/3 cubic foot, and $7.80 is “about” twice $3.60. The big packages, then, give about 15 times the shavings for a little over twice the price. (The exact difference in unit pricing is 7.98 times cheaper.)
Well … at least it didn't involve calculus! 😀