[yonran]

> I think Google moved it from AOSP to the Google Play Services several years ago, but the old source is still available.

For the curious, here is the source of ExactCalculator from the commit before all files were deleted: https://android.googlesource.com/platform/packages/apps/Exac..., and here is the dependency CR.java https://android.googlesource.com/platform/external/crcalc/+/...