6th Class Chapter No 10 - Motion And Measurements in Science for CBSE NCERT
Measurement: Comparing an unknown quantity with some known quantity is called measurement. Result of Measurement: The result of measurement has two parts; one part is the number and another part is the unit. The known quantity which is used in measurement is called a unit. For example; when you say that your height is 150 cm then the measurement of your height is being expressed in a number, i.e. 150 and a unit, i.e. centimeter.