- Plus is a function that does addition (summation) of expressions. The expression Plus[a,b,c,…] is commonly represented using the shorthand syntax . Special cases include Plus, which is taken to be 0, and Plus[x], which is taken to be x.
- Plus sorts its arguments and collapses any terms of the same type. Plus also threads element-wise over lists.
- To perform summation at a particular level of a list or to apply compensative summation to reduce numerical error for inexact summands, the function Total can be used. Accumulate gives a list of the successive accumulated totals of elements in a list. AddTo, Increment, and PreIncrement can be used to increase the value of a given variable. Minus gives the arithmetic negation of an expression, and Subtract gives the difference of two numbers.
- Summation of a function over a range or list of arguments is done using the function Sum.