Adidas has been the best fit for my tall guys. Some brands seem to only offer "Tall" in their larger sizes, but we've managed to find Adidas in "Small Tall". Even their regular length pants fit better than other track pants because they're so slim/tapered - with the right socks they look okay a few inches above the ankle. https://www.adidas.ca/en/tiro-19-training-pants/D95958.html

What method is she using to subtract? If she's trying to mentally subtract 153 - 6 using regrouping, that's a lot of information to keep in her working memory! Does she know how to "bridge through 10" when subtracting? 153 - 6 can be made easier: 153 - 3 - 3

The silent -e in are truly doesn't serve any function, so we know it's just there for historical/etymological reasons. From David Crystal's The Story of Be: A Verb's-Eye View of the English Language: "In Old English, three forms competed for the role of a present tense of be. One set clustered around a form usually shown as sind in the grammars (as in modern German), which had such variants as sindan, synden, and sint. These lasted into the early Middle English period: the latest citation in the OED is for 1300. But by then, the other two forms had become dominant: one developed into modern are; the other into modern be. We see the are set starting out in Old English in such dialect forms as earon and earan (showing an inflectional ending) and developing in Middle English as aren, aryn, eryn, eren, and many other variants until the -n is lost and we get such forms as arre, er, and the first instances of are."