How do I count the amount of cells which has a number in it in two columns but not count it twice?

If you're grappling with the challenge of counting unique numeric entries across two columns without duplication, you're not alone. Many spreadsheet users face this issue when trying to derive meaningful insights from their data. Fortunately, there's a straightforward solution that harnesses the power of formulas to achieve accurate counts. In this guide, we'll reveal how to effectively count cells containing numbers in both columns while ensuring that each entry is counted only once.