First, you need to save the file in PDF format, and elect to save everything. Not just "forms for your records" or "forms required for filing/mailing". You need to save absolutely everything.
In the saved PDF file there will be two form 4562's *for* *each* *property*, that prints in landscape format. One is titled "Depreciation and Amortization Report" and the other is "Alternative Minimum Tax Depreciation". The first one is the one most commonly used, as the second one only matters when AMT comes into play; which isn't all that common for most folks.
As for "the math used", it's covered in detail in IRS Publication 946 at https://www.irs.gov/pub/irs-pdf/p946.pdf
The worksheet starts at the bottom of page 37. For domestic residential rental real estate use table A-6 on page 72.
