Answer:
Mary has used chunking to improve storage in short-term memory.
Step-by-step explanation:
Chunking is a common strategy for better memorization of information. It consists of grouping pieces of information into chunks, or larger pieces, which helps increase the amount of information one can recall. That is what we often do with phone numbers or, as is the case with Mary, credit card numbers. It is easier to remember the chunks of numbers than to try to recall the whole thing or each number separately.