The answer provided is only based on sthree dharma;
Women need not have garlands while doing japa, they can easily keep count with their fingers.
Acharya would have initiated the proper form to do japa during mantropadesam. Excluding the thumb, if you count with the other four fingers in a clockwise direction, the tally would be 10; that is you should start your count on the index finger from down and when you reach your middle finger the total would be ten; you can count by keeping tabs mentally in this method. Generally, women do japa till 108 times and not more than this. So, this method of counting is easy; our elders also follow this method.