28/Historical Note

Historical Note on $28$

There are approximately $28$ days in the lunar cycle.

This is probably the origin of the widespread cultural custom of splitting time both into $7$-day chunks called weeks, and also the year into $12$ approximately $28$-day chunks called months.

There are $28$ pounds avoirdupois in one quarter.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $28$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $28$