The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From King's Apps:
Simply Addition is an app that allows the user to practice simple basic addition facts or extend the users ability to work out complex addition problems up to three digit numbers. Users can control the number of digits used to generate the problems. From one digit to three digits can be seclected by the user. Users also can control the number of questions given during one session. If a wrong answer is given by the user, the correct answer is shown before the next problem is given. Sound feedback is provided to the user for correct and incorrect answers. If you or your child are looking for a program to help improve his or her addition skills, this just might be the app for you.If you have any comments, suggestions, or constructive criticism please fell free to email me (email@example.com) or go to my website (http://kingsapps.webs.com/) and click on the tab that says "Contact Us". Thanks for your time!