You do have legitimate options to get a digital version:
: Use the included answer key to check your work immediately. Pay close attention to particle usage and verb conjugations, which are common sticking points at the intermediate level Habitual Review
Focuses on sentence patterns, word forms, and choosing correct structures based on the lesson's themes.
Minna no Nihongo Chūkyū 1 Hyōjun Mondaishū: A Comprehensive Report