tenthousandths

A tenthousandth is the unit equal to one part in ten thousand; in decimal notation its value is 0.0001, and it is the fourth digit to the right of the decimal point.

The name derives from the phrase ten-thousandth. The singular form is ten-thousandth (or one ten-thousandth), representing the fraction 1/10,000; the plural ten-thousandths or tenthousandths can refer to multiple such units or to zeros in that decimal place.

In measurement and calculation, the tenthousandth is used to express precision at the ten-thousandth level. For example, 0.0001 meters is one tenthousandth of a meter, and 0.0001 liters is one ten-thousandth of a liter. In percentage terms, 0.01% corresponds to 0.0001 in decimal form, illustrating how the tenthousandth relates to common fractional representations, such as 1/10,000.

In the decimal place value system, tenths correspond to 10^-1, hundredths to 10^-2, thousandths to 10^-3, and ten-thousandths to 10^-4. The concept also appears in other bases, where analogous terms denote successive fractions of the base. The tenthousandth thus serves as a standard reference for describing small quantities in mathematics, science, and engineering.