To use Proportions Calculator is easy. Just enter 3 numbers in any 3 entry boxes and press calculate to find the unknown value.
For practical examples of using this app see the examples page.
To hide the pop up keyboard use the back button on your device.
Use the A<->B button to swap the values of A and B.
Each value has a separate clear button to make changing values easy.
The reduced ratio results are only meaningful for ratios of whole numbers but are displayed for all results. Euclid's Algorithm is used for reducing the ratios.
The menu (or action bar depending on the Android version) has selections for:
Errors will be displayed as pop up toasts for: