I've started using a keyboard with no numeric pad to cut down on space. Unfortunately a program I use has a function which is locked to the number pads + and - keys. I thought there would be some kind of way to access these key presses in the form of a key combination or shortcut but I can't find any. 
Does anyone know of anyway I can initiate these key presses in Win10 via key presses on my tenkeyless keyboard?
Any advice greatly appreciated

Does anyone know of anyway I can initiate these key presses in Win10 via key presses on my tenkeyless keyboard?
Any advice greatly appreciated