AddTo 
AddTo
x+=dx
adds dx to x and returns the new value of x.
Examples
open all close allBasic Examples (1)
Scope (4)
The first argument to AddTo need not be a symbol:
Properties & Relations (4)
AddTo is a short form of this assignment:
PreIncrement is a special case of AddTo:
SubtractFrom is closely related:
A related operation for lists is AppendTo:
Wolfram Research (1988), AddTo, Wolfram Language function, https://reference.wolfram.com/language/ref/AddTo.html.
Text
Wolfram Research (1988), AddTo, Wolfram Language function, https://reference.wolfram.com/language/ref/AddTo.html.
CMS
Wolfram Language. 1988. "AddTo." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/AddTo.html.
APA
Wolfram Language. (1988). AddTo. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/AddTo.html