If I wanted to see where the number that shows on line 23 on form IA1040 comes from. Where do I look for it in TurboTax 2013?

On my 2013 tax return, there is a number on line 23 Iowa Capitol Gain Deduction Certain Asset Sale on the form IA1040? I need to know where this number comes from, so I can look it up. Thank you.