Decomposing 108 into factors one step at a time:
108
color(white)("XXX")=2xx54
color(white)("XXX")=2xx2xx27
color(white)("XXX")=2xx2xx3xx9
color(white)("XXX")=2xx2xx3xx3xx3
color(white)("XXX")=2^2xx3^2xx3
sqrt(108) =sqrt(2^2xx3^2xx3)
color(white)("XXX")=sqrt(2^2)xxsqrt(3^2)xxsqrt(3)
color(white)("XXX")=2xx3xxsqrt(3)
color(white)("XXX")=6sqrt(3)