Let's work this example together. It will make clear the whole idea of regrouping whole numbers.
Regrouping whole numbers is a free educational video by Khan Academy.It helps students in grades 5 practice the following standards 5.NBT.A.1.
1. 5.NBT.A.1 : Recognize that in a multi-digit number, a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left. .