Hi, @jacknguyen101.
You use the latest values you have computed. If you look closely at the formulas, you’ll see you’re updating running_mean and running_var over time. If, for some reason, you wanted to keep all the intermediate values, you’d have to explicitly save them somewhere else (as @ajaykumar3456 did when he ran his own experiment).
You may find this post useful too.
Let me know if that helped 