Formula: FV = PV × (1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)]
Where PV = present value, PMT = monthly contribution, r = annual rate, n = compounding periods per year, t = years.
$10,000 invested at 7% for 30 years grows to ~$76,000. Adding $500/month makes it grow to ~$700,000+. The difference shows how regular contributions supercharge compound growth.