Android app made using html, css, javascript to convert numbers into other formats(binary,decimal,hexadecimal,octal) and perform arithmetic operations among these 2 no. Place all the files inside directly into zip file and use Adobe Phonegap online utility to create Android,ios and windows app using same coding.
For Android you will require sign key. To generate sign key, have a look at http://docs.build.phonegap.com/en_US/signing_signing-android.md.html