What is the usage of "down" here? How can I use in other situation?
Native speaker’s answer
Rebecca
In this context, "down" means to restrict or to limit the possibilities to a specific area; to be exact in something. In this video, Walmart's new technology is able to locate the item you need to the exact aisle that it is located in. There are several definitions of "down" and it can be a little tricky to figure out how to use them all correctly. To use "down" in a similar context as it is being used in this video, you need to make sure it is emphasizing exact location, exact amount, etc. Here are a few examples of it being used. Ex: The army fought valiantly. Down to the last soldier. Ex: She ate all of the brownies. Down to the last brownie crumb. Ex: I have calculated my monthly expenses down to the last penny.