Knuckle_mnemonic
Knuckle mnemonic
Mnemonic for the number of days in each month
The knuckle mnemonic is a mnemonic device for remembering the number of days in the months of the Julian and Gregorian calendars.
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One-handed
One form of the mnemonic is done by counting on the knuckles of one's hand to remember the number of days in each month.[1] Knuckles are counted as 31 days, depressions between knuckles as 30 (or 28/29) days. One starts with the little finger knuckle as January, and one finger or depression at a time is counted towards the index finger knuckle (July), saying the months while doing so. One then returns to the little finger knuckle (now August) and continues for the remaining months.
One variant of this approach differs after reaching the index finger knuckle (July): instead of wrapping around back to the little finger, some people reverse direction and continue from the index finger knuckle (counting it for both July and August) and ending on the middle finger knuckle.
Two-handed
Others use two hands: starting with the little finger knuckle of the left hand, proceeding to the left index finger knuckle, then (swapping hands) jump to the right fist's index finger knuckle for August, finishing on the knuckle of the right ring finger.
- Lardner, Dionysius, ed. (1855). The Museum of Science and Art. Vol. 5. London: Walton and Maberly. p. 152.
When we close the hand there are four projecting knuckles of the four fingers, with depressions between them. If we give the knuckles and intermediate depressions the names of the successive months, recommencing from the first knuckle, after having once gone over them, we shall find that the months of thirty-one days are those which fall upon the knuckles. Also, in easier words, the gaps between the knuckles indicate months with not 31 days but 30 (excluding February which is 28/29).