Example: I want $300 in BTC. I can look up the current actual price of a WHOLE BTC; the atm displays the inflated, fee-inclusive price of a WHOLE BTC. What is the smallest number of mathematical steps to determine the amount of $ I need to feed the machine in order to wind up with $300 worth of BTC? (Obviously, the numbers will change while feeding the machine, but should be close enough for practical purposes...)
I do not think the feeling that will be deducted will be displayed, but, like we have ones commented, try to contact the atm's customer care care near your location. Or, maybe you do not know how beneficial coinatmradar can be. You can use it to check for the bitcoin atms near your location, you can use it to even trace the atm, the number and email you can contact the company managing the ATM is there also. Just check coinatmradar.com for this.
Assuming The price of bitcoin is $17000
The amount you want to buy is $300 like you commented
The transaction feels is 10% (the fee are usually high and always in percentage of btc amount you want to buy)
Fee is 10%, 10% of $300
10% of $300 =
$300 * 10 100 = $30
$300 - $30 =
$260 is what you will be able to buy.
1 btc = $17000
X btc = $260
Then cross multipleX btc =
1 btc * $260 $17000
X btc = 0.0152941176
After $10% fee is deducted, you will be given 0.0152941176 btc as the bitcoin purchased.