Please watch my previous free math tutoring videos on Mental Math before watching this video. Understanding mental math within twenty is foundational to understanding all mental math.
The concept in this free math tutoring video is slightly easier than talking about tens because we call numbers in the hundreds place, hundreds. This is not the case with the tens place. We say “twenty,” not “two-ten” or “thirty,” not “three-ten” as they do in other countries. Working on naming a certain number of hundreds when they add up to more than one thousand is the important concept here.