Calculator Using Object Oriented Programming

[Fallen]

That cant be efficent lol
This may help you a bit, I threw it together real quick

Code:

#!/usr/bin/env python

class Calculations( object ):
    def Addition( self, Numbers ):
        return sum( Numbers )
    def Subtract( self, Numbers ):
        Total = Numbers[ 0 ]
        for Index, Num in enumerate( Numbers ):
            try: Total -= Numbers[ Index + 1 ]
            except IndexError: return Total
    def Multiply( self, Numbers ):
        Total = 1.0
        for Num in Numbers: Total *= Num
        return Total
    def Divide( self, Numbers ):
        Total = Numbers[ 0 ]
        for Index, Num in enumerate( Numbers ):
            try: Total /= Numbers[ Index + 1 ]
            except IndexError: return Total
Numbers, Counter, Answer = [], 0, True
while Answer:
    Counter += 1
    try:
        Answer = int( raw_input( "Number %i: " % ( Counter ) ) )
        Numbers.append( Answer )
    except ValueError: Answer = False
if len( Numbers ) < 2: print "Error: You need atleast two numbers..."
else:
    Methods, Method = ["add", "subtract", "divide", "multiply"], False
    while not Method in Methods: Method = raw_input( "Add/Subtract/Divide/Multiply? : ").lower()
    Math = Calculations( )
    if Method == Methods[ 0 ]: print Math.Addition( Numbers )
    if Method == Methods[ 1 ]: print Math.Subtract( Numbers )
    if Method == Methods[ 2 ]: print Math.Divide( Numbers )
    if Method == Methods[ 3 ]: print Math.Multiply( Numbers )