5/Historical Note

Historical Note on $5$

The number $5$ was the number associated by the Pythagoreans with marriage, the sum of $2$, the first female number, and $3$, the first male number.

According to Plutarch, the Pythagoreans also associated $5$ with nature, on account of its automorphic property.

The number $5$ is expressed in Roman numerals as $\mathrm V$.

It has been suggested that this originates from the shape of one hand held up showing the full $5$ fingers.

Sources

• 1980: David M. Burton: Elementary Number Theory (revised ed.) ... (previous) ... (next): Chapter $1$: Some Preliminary Considerations: $1.3$ Early Number Theory
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $5$
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $50$
• 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {A}.2$: Pythagoras (ca. $\text {580}$ – $\text {500}$ B.C.)
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $5$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $50$