onethird

One third is a numerical value and a fraction representing one part when a whole is divided into three equal parts. The fraction is written as 1/3 and is a unit fraction, the reciprocal of 3. In decimal notation, 1/3 equals 0.333... with the 3 repeating indefinitely.

In arithmetic, 1/3 illustrates how fractions add and multiply: 1/3 + 1/3 = 2/3, and multiplying 1/3 by 3 yields 1. The ratio form is 1:3, and it is equal to approximately 33.333 percent.

Applications include time, where one third of an hour is 20 minutes; in cooking and measurement, one third of a liter is 333.333... milliliters. In geometry, dividing a circle into three equal sectors creates angles of 120 degrees at the center. In probability and statistics, an event with probability 1/3 has about a 33.3% chance.

Origin and notation: The concept of thirds appears in many numeral systems and is commonly expressed across mathematical texts. 1/3 is among the simplest unit fractions and plays a foundational role in fraction arithmetic and in expressing proportions.