Pi is an irrational number, approximated at 3. "Approximating pi may not give the exact answer when using formulas for circle area or circumference." For better accuracy, use more decimal places or a calculator with the exact value of pi. Use a symbol like π/3 as an alternative. Note that even with the exact value of pi, there may be slight errors in calculations. Reliable sources only - Mathworld and Wolfram. Used com and nist. gov to answer question. Make text shorter.