percentof

Percent of is a mathematical expression that relates one quantity to another by indicating how many parts out of one hundred the first quantity represents of the second. It is commonly expressed with the percent sign (%) and used to compare amounts, compute proportions, and describe changes relative to a base value.

The basic relationship can be written as part = (percent / 100) × whole. To find the percent when the part and whole are known, use percent = (part / whole) × 100. To find the whole from a part and a percent, use whole = part ÷ (percent / 100). Converting between percent and decimal forms involves dividing or multiplying by 100 (for example, 25% = 0.25).

Applications include finance (interest rates, discounts, tax), statistics (population percentages, survey results), education (grades), and data presentation. Common pitfalls are confusing percent change with percentage points, using an incorrect base when computing a percent, and forgetting to convert between percent and decimal form in calculations.

The term percent comes from the Latin per centum, meaning "by the hundred." Because percent depends on the chosen reference value, clarity about what constitutes the whole is essential for correct interpretation and communication.