If diameter = 4,
then radius = 4/2 = 2m.
Formula for the Circumference of a Circle = 2[tex]\pi[/tex]r
2[tex]\pi[/tex]r = 2 x 22/7 x 2
2 x 22/7 x 2 = 4 x 22/7 = 88/7
= 12.5714286 cm.
It can be also be rounded up into 12.6 cm.
So, the Circumference of the Circle is 12.6 cm or 12.5714286 cm.