Deductions & credits

Yes, I mistakenly used the message area ;(

Read publication 936 and it is not helpful. Here is my issue

1. Full year -  Owned a vacation home, average for the year 57, 600 - mortgage interest 5744/yr. Didn't have a primary home since <i was living in an appt while my home was being built - LOAN 1

2. Bought a home May 4th - Loan total 632,000. Made payments and sold July 31st - mortgage interest 4900 for those 3 months. LOAN 2

3. relocated and Bought Home 8/1 - loan total 960,000 and still own it - mortgage interest is $7650. -LOAN 3

Total mortgage interest paid is 18290 and turbo tax calculates a little over 10,300 and am not sure the math behind that.

I´ve done it 2 different ways and got 2 different values:

I did an average balance per month by adding the statements. So Jan through April loan 1, May through Jul loan 1 and loan 2, and Aug through Dec Loan 1 and 3.

Option 1: I sum it all and divide by 12 it says my average balance is 612,000, below the 750,000 therefore all deductible

Option 2: Also add the mortgage interest for all loans each month, then take the ratio of 750000 to the monthly loan balances and adjust the monthly mortgage interest  - then add them all up - that will say about 15200 is deductible. Im ignoring that LOAN 1 can be 1million vs 750K

Option 3 is what turbo tax is doing which I haven't figured out ow they got there

thanks for the response!