The core, simple formula for a percentage is
The term is conceptually identical to one "cent" being 11001 over 100 end-fraction of a dollar, thus 37 cents is 37 percent of a dollar. Deep Mathematical Meaning per centum
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. The core, simple formula for a percentage is
"Percent" (one word) is standard American English, while "per cent" (two words) is more common in British English. How to Pronounce Percent - Deep English per centum
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).