Adding Machine 10Key Universal is a versatile calculator app that behaves like a true '10 Key' or 'printing calculator'. Developed by Richard Silverman, this app offers a range of features that make it a useful tool for business and productivity purposes.

With Adding Machine 10Key Universal, users can perform calculations with ease. The app allows for reverse operator entry, obtaining percentages by multiplying and adding to a stream of numbers, and obtaining a total by pressing the asterisk (*) key. It also features a full-sized keypad with TypeTone, an audio aid that helps guide the user's finger back to the center of a key.

In addition to its calculation capabilities, Adding Machine 10Key Universal allows users to review and edit numbers, add or delete lines, and save and retrieve paper tape files. The app also offers the option to export paper tape files to iBooks, Dropbox, email, or other printing utilities.

Try before you buy with the 'Adding Machine 10Key Univ Lite' version available in the App Store. Currently featured in iTunes' "What's Hot" in the Finance Category, Adding Machine 10Key Universal is a powerful and convenient calculator app for iPhone users.