Worked great for me. Had no trouble with the app. Not sure what "agrenergy" or "mommum" had a grief about. The sliders make it better than the other ones I've tried. Update has finally fixed the keyboard thing so I can enter values numerically.
@Penn hit the lock icon for the one you want to calculate (that is, "unlock" the one you want to solve for), then move the sliders of the other 3 values to calculate - it computes as you make the changes. See my support site for a video example!
This awesome calculator lets you compute and modify the ideal gas equation PV=nRT using any of the 4 parameters as the free parameter and with different units for P, V, and T. The convenient sliders let you see the effect of changing one of the independent parameters on the dependent one giving you a very natural understanding of how the relationship works. Students, educators, researchers, and those interested in computational chemistry will all appreciate the convenience of seeing the computation recomputed for different units with a simple touch of the selector bar.