how to find equivalent resistance of complex circuits in less time ?

If we are provided with a complex resistance then most of the chances are there that it may be a wheatstone bridge so one or some resistance will be neglected ..otherwise if it is symmetry then we can divide it to half exactly between the two terminals (suppose A and B) where the resistance is to be determined ..then which resistances are divided into half we can take their value half of the original and determine the resistance of one half .At last multiply it by 2 to get the answer ...remember it is only for symmetrical arrangement .

If all identical resistance are connected in series having same value then by using formula R=number of resistance multiple of value of resistance... And connect in parallel then follow the formula. R=r/n ..