Why you can't hold 12 digits but can hold 3 years: working memory chunks
30seconds
Try to hold 149217891945 in your head and it slips away. Read it as 1492, 1789, 1945 and it sticks. The digits are the same; the number of things to hold is not.
Working memory is a tiny scratchpad, and what limits it is the number of chunks, not digits. Try a 5-second memory test with different groupings and see your own scores change.
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