For legitimate access, the textbook is available through academic retailers like Pearson or platforms such as Amazon. (PDF) Thomas' Calculus - George B. Thomas' - 13th Edition

The late George B. Thomas Jr. revolutionized math education by moving away from pure memorization toward intuitive understanding. The 13th Edition, updated by Maurice D. Weir, Joel Hass, and Frank R. Giordano, retains Thomas’ original vision while incorporating modern pedagogical tools.

However, if you own a physical copy and want a digital backup, scanning your own purchased book for personal use remains a legal grey area that most students utilize.

A: Usually, yes. However, the problem numbers change significantly between editions. If your homework is "Section 3.2, problems 1-20," the 12th edition will have different numbers. You would need a friend with the 13th to cross-reference.