Samsung Galaxy Tab S2 unable to enter equations/calculations

[Schtimpy]

I run TouchDRO Plus on a Samsung Galaxy Tab S2. When I need to enter a dimension into an axis I do not get a "keybord" that allows me to enter an equation/calculation. I have tried the default Samsung keyboard, as well as Gboard, but to no avail.
Any ideas for a workaround: I believe it is something unique to Samsung tablets.

 

[Schtimpy]

Issue is no longer: the +/-* and . are displayed across two "small keyboards" rather than together in a typical "numerical" or "calculator" keypad layout.
While it is a bit of a strange format/layout spread across the two layouts, the functions are actually all there.