减法是寻找两个数的差的算术运算，可视为「加法的逆运算」。减法是符号是减号（）。加、减、乘、除合称四则运算。

在数式里，称为被减数，称为减数，是和的差。

减去一个数等于加上这个数的相反数。若果被减数小于减数，得出来的差将会是负数。

Subtraction is a mathematical operation that represents the operation of removing objects from a collection. It is signified by the minus sign (−). For example, in the picture on the right, there are 5 − 2 apples—meaning 5 apples with 2 taken away, which is a total of 3 apples. Therefore, 5 − 2 = 3. Besides counting fruits, subtraction can also represent combining other physical and abstract quantities using different kinds of objects including negative numbers, fractions, irrational numbers, vectors, decimals, functions, and matrices.