Question

You took a 30-year $750k mortgage that charges 3% interest per year. What percent of the mortgage had you paid off at midpoint, i.e., after making your 180th monthly payment?

Answer 1

Loan value = $750,000

Monthly Interest Rate = 3%/12 = 0.25%

No of Monthly payments = 30 years*12 = 360

Calculating the Cummulative Principal paid off till 180th monthly payment using Excel "CUMPRINC" function:-

So, Cummulative Principal paid off till 180th monthly payment is $292,120.72

- Percent of the mortgage had you paid off at midpoint=  Cummulative Principal paid off till 180th monthly payment/Loan amount

= $292,120.72/$750,000

Percent of the mortgage had you paid off at midpoint = 38.95%

If you need any clarification, you can ask in comments.    

If you like my answer, then please up-vote as it will be motivating