Because Math Makes Sense is a copyrighted publication (Pearson Canada), full PDFs of the answer keys are not legally sold as standalone products. However, there are "better" alternatives:
If a concept is difficult, use interactive tools like the Math Learning Center Geoboard to visualize geometric problems. Because Math Makes Sense is a copyrighted publication
If you are stuck on a problem, understanding the concept is better than just finding the answer. Here is a breakdown of the major units in Math Makes Sense 4 and how to solve them. Because Math Makes Sense is a copyrighted publication
Knowing that a guide is available to clear up confusion lowers frustration levels for struggling learners. Because Math Makes Sense is a copyrighted publication