Question 121460
This is a future value of an oridinary annuity problem.
The formula is 
{{{FV=PMT(((1+i)^n-1)/i)}}}
where 
FV is the future value (what you're looking for)
PMT is the payment made during the period ($250)
n is the total number of periods (40 years)
i is the period interest rate (6% per year)
{{{FV=PMT(((1+i)^n-1)/i)}}}
{{{FV=250(((1+.06)^40-1)/.06)}}}
{{{FV=250(((1.06)^40-1)/.06)}}}
{{{FV=250((10.2857-1)/.06)}}}
{{{FV=250(9.2857/.06)}}}
{{{FV=250(154.762)}}}
{{{FV=38690.49)}}}
The future value would be $38690.49.