This is a short multiply node of (up to 10 scalar inputs) I wrote in Maya c++ api. Hope you find it helpful.
Here's are some images of it in use:
a small tip i ran into when running this was in the compute its important to use the right conversion when working with inputs via dataHandle. For example if attribute is float need asFloat (when i first wrote it i mistakenly used asDouble and the tool was bugging out). Hope this tip is helpful.