The sum(...) function has only one variation, not counting syntax variations. It computes the sum of a list of numbers ignoring null values. This function will only return null if all input values are null. The result is an Integer value if all inputs are Integer values, otherwise the result is a Float value.

Syntax:
sum( list-of-numbers )
first-number.sum( list-of-numbers )

Parameter	Description
list-of-numbers	A comma separated list of Integer and/or Float values.
first-number	The first number which would be in the list-of-numbers.