Code for Multiplying Fractions in Python

# A class
class TimesFraction:

    # Simulate a constructor
    def __init__(self, fractions):
        self.numerators   = fractions['numerators']
        self.denominators = fractions['denominators']

        self.trial_factor = 0
        self.n_index = 0
        self.d_index = 0
        self.answer = [1, 1]

        # set trial_factor to the highest value amongst
        #both numerators and denominators
        for numerator in self.numerators:
            if numerator > self.trial_factor:
                self.trial_factor = numerator
        for denominator in self.denominators:
            if denominator > self.trial_factor:
                self.trial_factor = denominator

    # Returns a dictionary of the new numerator and denominator
    def doMultiply(self):
        # STEP 3:
        # We are counting down to test for mutual factors 
        while self.trial_factor > 1:
            # STEP 1:
            # iterate through numerators and check for factors
            while self.n_index < len(self.numerators):
                self.mutual_factor = False
                if self.numerators[self.n_index] % self.trial_factor == 0: # do we have a factor
                    # iterate through denominators and check for factors
                    while self.d_index < len(self.denominators):
                        if self.denominators[self.d_index] % self.trial_factor == 0: # is this factor mutual?
                            self.mutual_factor = True
                            break # stop as soon as we find a mutual factor so preserve the corresponding index

                        self.d_index += 1

                    break # stop as soon as we find a mutual factor so as to preserve the corresponding index

                self.n_index += 1

            # STEP 2:
            # where we have a mutual factor
            if self.mutual_factor:
                self.numerators[self.n_index]   /= self.trial_factor
                self.denominators[self.d_index] /= self.trial_factor
                continue # continue with next iteration repeating the current value of trial_factor

            self.n_index = 0
            self.d_index = 0
            self.trial_factor -= 1


        for numerator in self.numerators:
            self.answer[0] *= numerator
        for denominator in self.denominators:
            self.answer[1] *= denominator
            
        return {'numerator':int(self.answer[0]), 'denominator':int(self.answer[1])}

#!/usr/bin/python
from MultiplyFraction import TimesFraction

##
 # Multiplying fractions
 ##
numerators   = [16, 20, 27, 20]
denominators = [9, 9, 640, 7]
fractions = {'numerators':numerators, 'denominators':denominators}

print('\n    Solving:\n')
# Print as fraction
for numerator in fractions['numerators']: print('{:13d}'.format(numerator), end='')
print('{}{:>12}'.format('\n', ' '), end='')
for wasted in range(len(numerators)-1): print('{}'.format('-     X      '), end='')
print('{:>1}'.format('-'))
for denominator in fractions['denominators']: print('{:13d}'.format(denominator), end='') 
print('\n\n')

# use the MultiplyFraction class
mul_fract = TimesFraction(fractions)
fraction = mul_fract.doMultiply()

print('{:25d}'.format(fraction['numerator']))
print('{:>25}'.format('Answer   =   -'))
print('{:25d}'.format(fraction['denominator']))


print('\n\n')