Accurate to n Significant Figures/Examples/Pi to 5 Figures

Example of Accurate to $n$ Significant Figures
The constant pi ($\pi$) expressed accurate to $5$ significant figures is:
 * $\pi \approx 3 \cdotp 1416$

Proof
We start with the decimal expansion of $\pi$:

We note that:
 * $3.1416 - 3.14159 < 3.14159 \ldots - 3.1415$

and so $\pi$ rounded to $5$ significant figures is:
 * $3.1416$