Answer:
[tex]\bold{\pi=\dfrac c{246}}[/tex]
Step-by-step explanation:
[tex]{}\qquad \bold{c=2\pi r}\\\\{}\qquad\bold{c=2\pi\cdot123}\\\\{}\qquad\bold{c=246\pi}\\\\\div246\qquad\div246\\\\{}\quad\bold{\frac c{246}\,=\,\pi}[/tex]