Question

find the circumference of a circle whose radius is 15.4cm 

Answer 1

$r=15,4\ cm\\C=2\cdot\ \pi\ \cdot\ r\\C=2\cdot\ \pi\ \cdot\ 15,4\ cm\\C=30,8\ \pi\ cm$

$\pi\approx\ 3,14$

$C=30,8\ \cdot\ 3,14\ cm\\C=96,712\ cm$

Answer 2

π = 3,14

c = 2.π.r
c = 2.3,14.15,4
c ≈ 96,7