How do you calculate the number of put options to be purchased, choose an exercise price and the corresponding put premium, and calculate the total...

How do you calculate the number of put options to be purchased, choose an exercise price and the corresponding put premium, and calculate the total premium. Collecting the July 13, 2018 closing spot price then compare the July 13, 2018 spot price (1.1701) vs the exercise price, and then decide whether to exercise the option if the exercise price is greater than the spot price, OR let the option expire if the exercise price is less than the spot price.