Protsendid

Protsendid are a way to express a part of a whole as a fraction of 100. They are written with the symbol % and quantify how large a portion is relative to a hundred units. The concept is the same across languages; in Estonian, protsendid translates to percentages in English, and the term stems from Latin per centum (by the hundred).

To work with percentages, it is common to convert between percents, decimals and fractions. A percent value p% equals p/100 in decimal form. To convert a decimal d to a percent, multiply by 100 and add the percent sign. To find p% of a number X, compute (p/100) × X.

Percent change expresses how much a value has risen or fallen relative to its previous value: ((new − old) / old) × 100%. For example, a rise from 80 to 100 is ((100 − 80)/80) × 100% = 25%.

Percentages have wide usage in finance, statistics and everyday life: discounts and tips, interest rates, share of a population, exam grade distributions, polls and market research. Common pitfalls include mixing up percentage points with percentages, and using an inappropriate base value when reporting changes. Rounding can also affect interpretation, especially with many decimals or small bases.