Download of Addition 1.0.7 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program lies within Education Tools, more precisely Teaching Tools. This Mac app was originally produced by fishdog.net. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Addition is fun and educational Mac OS X app for both children and parents. All you ave to do is to click numbers to solve equations. You can also adjust the level for harder problems, or for word-based addition. Children who need help can get hints from the jumping dog (that will help to calculate the right answer).
You may want to check out more software for Mac, such as Math Fun 1st Grade: Addition & Subtraction, Arithmemouse Addition Subtraction Game or MEGA Addition FREE, which might be related to Addition.