Answer:
present value = $500,000/1.08 + $515,000/1.08² + $600,000/1.08³ = $1,380,791.80
you calculated the present value correctly, assuming that you receive the annual payments at the end of each year (ordinary annuity).
but if you receive the annual payment at the beginning of the year (annuity due) = $500,000 + $515,000/1.08 + $600,000/1.08² = $1,493,255
it's not exactly the same value, but it is much closer and you could assume that the difference is due to rounding: ($1,493,255 - $1,495,370) / $1,495,370 = -0.1%
