求搵H.C.F & L.C.M.的最快方法!

Take out the common factor.
Let a be the common factor andax be the first no.,ay be the second.
ax,ay=a(x,y)
e.g.
6,18
(6,18)
=2(3,9)
=2*3(1,3)
H.C.F=2*3=6.

L.C.M. short division/

靠直覺!!!!靠直覺!!!!