Assessing the Reasonableness of Sums Using Regrouping

The video tutorial explains how to assess the reasonableness of sums using regrouping. It introduces the concept of checking answers for mathematical sense and provides examples with Anthony and Colin's addition problems. The tutorial demonstrates how to use regrouping and estimation to verify if the sums are reasonable, highlighting the importance of checking both the tens and hundreds places. The video concludes by emphasizing the effectiveness of the regrouping strategy in estimating sums accurately.

What steps did the teacher take to estimate the sum of 300, 75216, and 911?

Why was Colin's answer of 1782 considered unreasonable based on the regrouping strategy?