The average person's short-term memory can only hold 7 pieces of information for about 30 seconds. If you want to get something into your long-term memory, you're going to need to remember it for at least 30 seconds.
This is probably why it's easy to forget someone's name moments after hearing it. The name only sticks in your brain for 30 seconds, and unless you do something to push it into your long-term memory, you are going to forget it.
To get more than 7 items at a time into your long-term memory, you can try the Chunking Technique (*see below). Repetition can also help.
But remember, having a limited short-term memory is a good thing! Imagine how cluttered your mind would be if you remembered every single thing that went into it.
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(*)Chunking: The technique of taking smaller objects and grouping them into larger objects so they can be more easily remembered. It's much easier to remember 65-74-81-32 than it is to remember 65748132.
Try remembering the letters TRTESEL. Now try remembering the same letters in this order: LETTERS. Because your brain is remembering a word instead of 7 random letters, it doesn't have to work as hard. Essentially, you have compressed more information into a single chunk.
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source: http://www.braingle.com