The term evolved over time. "Per" was often abbreviated to "p", and "cento" was contracted until it eventually became the modern symbol: %.
Percentages over 100% (e.g., 200%) signify a whole plus an additional amount (2 times the original amount). Related Technical Terms Per Mille (‰): Parts per thousand (1 in 1,000).
The phrase emerged from per centum (16th century), and its usage was heavily refined by Italian merchants, who frequently used "per cento" for calculating taxes, interest, and discounts.