One of the biggest mistakes a new investor can make is focusing on the purchase price without calculating what it will actually cost to own and operate the property. Before committing to a deal, here are five numbers worth understanding: 1. Total Cash Needed Look beyond the down payment. Include closing costs, inspections, initial repairs, and cash reserves. 2. Realistic Rental Income Research comparable rentals in the area. Base your estimates on achievable rents, not the highest listing you can find. 3. Monthly Operating Expenses Account for property taxes, insurance, maintenance, vacancy, property management, and other recurring costs. 4. Monthly Cash Flow Subtract operating expenses and mortgage payments from expected rental income. A property that looks profitable before financing may tell a different story afterward. 5. Unexpected Costs Roof repairs, plumbing issues, vacant months, and other surprises can quickly affect your returns. A reserve fund helps you prepare for the unexpected. The goal isn't just to buy a property. It's to buy one whose numbers make sense before you commit. Experienced investors, when you evaluate a first-time investor's deal, which number do you think they are most likely to overlook—and why