I discovered this recently when I found myself buying energy drinks every day. I decided that instead of going to the store 7 days a week I'll just stock up ahead of time. When shopping I found four packs and twelve packs. The four packs cost $5.98 and the twelve-packs cost $19.98. Do some quick math and you will find it cheaper to buy three four-packs totaling twelve cans rather than one twelve pack.
This is true with many other products but may not be as obvious such as a larger bottle of detergent or a larger box of crackers. Before you start bringing calculators to the grocery store I should let you in on a little secret. At almost all grocery stores you will find on the shelf a price tag. There are usually two prices displayed but many only pay attention to just the one which is the price of the container. The other one is much more useful and it is the price per unit. The price per unit allows for comparison shopping between two products of different sizes or quantities.
For example, you have two different brands of crackers each in the same size box. One contains 70 crackers for 1.25 and the other contains 100 crackers for 1.50. So, which one is cheaper? It appears the 1.25 is cheaper but the unit price will tell you that the first is .0178 per cracker making it 1.78 per 100 ct whereas the second is 1.50 per 100 ct. Therefore, the second is really the better deal.
It sounds confusing but the math has already been done. Just take a quick glance at the per-unit price to see what's really the better deal.
The estimated savings vary with this one but we assume the average household could essentially save approximately $40 a month off of their grocery bill following this advice. Therefore total PT savings over a year = $480.