A program that finds the total resistance of n parallel resistors

calculateParallelResistance.py

#!/usr/bin/python
import numbers

def findDivisor(num):
	# 2,3 are the most common divisor for many numbers hence going by divisor of 2,3 can be quicker
	# if not then by the same number as divisor
	if num%2 == 0:
		return 2
	elif num%3==0:
		return 3
	return num

def findLCM(lcmArray):
	lcm = 1
	while len(lcmArray) > 0:
		minOfLCMArray = min(lcmArray)
		divisor = findDivisor(minOfLCMArray)        

		for x in xrange(0, len(lcmArray)):
			Quotient = lcmArray[x]/divisor
			Reminder = lcmArray[x]%divisor
			if Reminder == 0:
				lcmArray[x] = Quotient

		lcm*=divisor
		minOfLCMArray = min(lcmArray)
		if minOfLCMArray == 1:
			lcmArray.remove(minOfLCMArray)
	return lcm

def totalParallelResistance(resistorList):
	lcm = findLCM(resistorList[:]) # [:] needed so that a copy of resistorList is passed and the resistorList object does not get manipulated
	# print resistorList
	
	numerator = float(0) # Needed so the the calculations have decimal values and not only integer values
	for resistor in resistorList:
		# print lcm/resistor
		numerator += lcm/resistor
	# print "numerator = %s" % numerator
	totalResistance = lcm/numerator
	print "Total resistance = %f Ohms" % totalResistance
	
def printSampleInput():
	print "--------------------------------------------------------"
	print "|\t\tVIEW THE SAMPLE INPUT BELOW\t\t|\n| Enter the resistors(Ohms) separated by commas: 4,6,12\t|"
	print "--------------------------------------------------------"
		
def getUserInput():
	user_input = []
	try:
		user_input = input('Enter the resistors(Ohms) separated by commas: ')
	except (SyntaxError, NameError): # will catch empty input, input as letters without quotes,
		print("Error: No valid input detected!")
		printSampleInput()
		exit(-1); # Exit with error
		
	if isinstance(user_input, tuple): # Check if the input was read as a tuple (meaning more than one input)
		resistors = [i for i in user_input] # Parses user_input and converts it from a tuple into a list
		
		for obj in resistors:
			if not isinstance(obj, numbers.Number): # check if all elements of list are numbers
				print("Error: Invalid input detected!")
				printSampleInput()
				exit(-1); # Exit with error
		return resistors
		
	elif isinstance(user_input, numbers.Number): # Only one input and that input is valid
		print "Total resistance = %f Ohms" % user_input
		exit(0) # Exit in good condition
	else: # At least one input and at least one invalid input
		print("Error: Invalid input detected!")
		printSampleInput()
		exit(-1) # Exit with error



inputs = getUserInput()
totalParallelResistance(inputs)