This document describes how to use a number line to add whole numbers. It explains that a number line is useful for additions that require carrying to the next multiple of ten. It demonstrates adding 9+7 and shows working through the stages on a number line. It then discusses adding larger numbers like 39+47, showing that you can either add the tens first and then the units, or the units first and then the tens, working through the stages on a number line both ways.