To answer the question "where did this number come from" you need your tax data file and a copy of Turbotax installed on your own computer. If you filed online using a paid version, call customer support to ask for a downloadable copy to install on your Mac or PC. You can download your tax data file from your online account. If you filed using the program installed on your computer, you already have the program and data file.
Open your data file in the program and click the "Forms" button at the top to switch to Forms mode. Go to form 1040 line 17, and double-click the number. That should bring up a worksheet that shows where the total came from. Double-clicking those numbers will take you to more specific worksheets for W-2s, 1099s, etc.
