Example: 28 + 17
Students will think28 plus something is going to get me to my next landmark number of 30.
I know that 28 plus 2 will get me to the landmark 30.
Since I am adding 17 altogether, I need to subtract 17-2 (the hop I already took) to equal 15. This tells me I still need to take a hop of 15 on the number line. If students cannot add 30 + 15 in their head, they can break apart the 15 in a way that is helpful to them. (10 + 5 hops, 15 single hops, etc.)