You are downloading the Mental Calculation XAP file v188.8.131.52 for Windows Phone. Mental Calculation is a free and useful Education app: This app help you to continuously improve your head calculation skills. Thanks to the many setting possibilities (Range of Numbers [1 to 9999], ... You can now download the offline XAP file to install & try it.
Download Locations for Mental Calculation 184.108.40.206 XAP file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Mental Calculation XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.