Investing $100 every month at a 7% average annual return grows to $121,997 in 30 years. You contribute $36,000 in total, and compound interest adds $85,997.

Key Numbers

• •Total after 30 years at 7%: $121,997
• •Total contributions: $36,000
• •Interest earned: $85,997
• •Starting with a $10,000 lump sum as well: $203,162