Create math exercises for 1st to 3rd grade. Addition, subtraction, multiplication and division

firstGradeCalc.py

#!/usr/bin/env python3
#
# This program prints out three colums of exercises, each time with the result next to it.
# Each column exists of 66 exercises.
#
# 1. Run the program
# 2. Print out the created text file to a DINA4-paper
# 3. Fold back the results of the first column
# 4. Fill in the results for the first column.
# 5. Unfold and check the results
# 6. Use the same method for the other two columns.

import os
import random
import sys
import datetime
import pytz


def addingSubtractingNatural(MAXINT):
    '''
    Generates a random addition or subtraction exercise with natural numbers (no negative numbers)
    MAXINT: the maximum number to be used in the exercise
        For first grade, MAXINT should be 20
        For second grade, MAXINT should be 100
    '''
    answerfield = ' = ... \t|\t'
    a = random.randint(0, MAXINT)
    operations = ('+', '-')
    operation = random.choice(operations)
    if (operation == '+'):
        b = random.randint(0, MAXINT-a)
        c = a+b
        return str(a) + ' + ' + str(b) + answerfield + str(c)
    elif (operation == '-'):
        b = random.randint(0, a)
        c = a-b
        return str(a) + ' - ' + str(b) + answerfield + str(c)


def multiplyDivideNatural(MAXINT):
    '''
    Generates a random multiplication or division exercise with natural numbers (no negative numbers)
    MAXINT: the maximum multiplicand (or multiplier) to be used in the exercise
        For second grade, MAXINT should be 10 (so the product is less than or equal to 100)
    '''
    answerfield = ' = ... \t|\t'
    a = random.randint(0, MAXINT)
    b = random.randint(0, MAXINT)
    c = a*b
    operations = ('x', ':')
    operation = random.choice(operations)
    if (operation == ':' and b == 0):
        # avoiding division by zero
        operation = 'x'
    if (operation == 'x'):
        # a*b = c
        return str(a) + ' x ' + str(b) + answerfield + str(c)
    elif (operation == ':'):
        # c/b = a
        return str(c) + ' : ' + str(b) + answerfield + str(a)


def main(argv):

    # with open('./exercise_adding_subtracting.txt', 'w') as f1:
    #     for lines in range(66):
    #         f1.write(addingSubtractingNatural(20) + '\t\t' + addingSubtractingNatural(20) + '\t\t'+ addingSubtractingNatural(20) + os.linesep)

    with open('./exercise_multiply_divide_'+ str(int(datetime.datetime.now(tz=pytz.utc).timestamp()))  +'.txt', 'w') as f1:
        for lines in range(66):
            f1.write(multiplyDivideNatural(10) + '\t\t' + multiplyDivideNatural(10) +
                     '\t\t' + multiplyDivideNatural(10) + os.linesep)


if __name__ == '__main__':
    main(sys.argv[1:])