Sorry to hear the math is a little difficult right now.
Won't be long until your grandson has that "AHA" moment.
He is blessed to have a caring grandparent to lean on.
Until you can locate a tutor...perhaps some of these may begin the
process. Lots of free online sites.
Free Math Games
Math Play - Free Online Math Games
Aha!Math - Online Math for Elementary and Middle School
Curriki