जोड़ने की प्रक्रिया के विरुद्ध प्रक्रिया को घटाना कहा जाता है। जब किसी संख्या अथवा अंक से किसी दूसरी संख्या या अंक को कम किया जाता है तो उसे घटाना कहा जाता है। घटाने को - चिह्न से प्रदर्शित किया जाता है, जिसे ऋण चिह्न कहते हैं।

Subtraction is one of the four arithmetic operations along with addition, multiplication and division. Subtraction is an operation that represents removal of objects from a collection. For example, in the adjacent picture, there are 5 − 2 peaches—meaning 5 peaches with 2 taken away, resulting in a total of 3 peaches. Therefore, the difference of 5 and 2 is 3; that is, 5 − 2 = 3. While primarily associated with natural numbers in arithmetic, subtraction can also represent removing or decreasing physical and abstract quantities using different kinds of objects including negative numbers, fractions, irrational numbers, vectors, decimals, functions, and matrices.