The official solution manual for "Calculus" by Tom Apostol is available, but it is not freely downloadable as a PDF. However, there are some alternatives:
You aren't just "plugging in" numbers; you are proving theorems. tom apostol calculus vol 2 solutions pdf
You must be aware: downloading a copyrighted Instructor’s Solutions Manual without authorization is a violation of intellectual property law. Wiley has been known to issue DMCA takedowns for host sites. The official solution manual for "Calculus" by Tom