1. The user asks to round only at the end of calculations. 2. This means you should carry out all intermediate steps with full precision. 3. Only after obtaining the final result should you round the number to the desired decimal places. 4. This approach avoids cumulative rounding errors and ensures the most accurate final answer. 5. For example, if calculating $\frac{2}{3} + \frac{1}{6}$, first compute exactly: $$\frac{2}{3} + \frac{1}{6} = \frac{4}{6} + \frac{1}{6} = \frac{5}{6}$$ 6. Then round the final result, e.g., $\frac{5}{6} \approx 0.833$ if rounding to three decimals. 7. Avoid rounding $\frac{2}{3} \approx 0.667$ and $\frac{1}{6} \approx 0.167$ first, then adding, as that would give $0.834$ which is less accurate. 8. So, the key rule: perform all calculations exactly or with full precision, then round only the final answer.