I am reposting this bit of code for those who want a simple way to call the calculator's intent on any phone. It took me a few hours to find this and thought others may find it helpful.
B4X:
Dim Pm As PackageManager
Dim Inte As Intent
Dim Packages As List
Dim st As String
Packages = Pm.GetInstalledPackages
For i = 0 To Packages.size - 1
st=Packages.Get(i)
If st.Contains("calc") =True Then
Inte=Pm.GetApplicationIntent(st)
If Inte.IsInitialized Then StartActivity(Inte)
Exit
End If
Next