This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Below is a table showing all the ways to add the numbers from 1 to 9. Each sum which is larger than 10 can be found by first making a 10. For example, ...

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