Quick and easy method for students to calculate the equivalent resistance of a Parallel Circuit using the inverse key of their calculators. If you would like to know how we know the formula for Parallel Resistance chick out this Khan Academy video. https://youtu.be/ZrMw7P6P2Gw
If on your computers calculator you do not find the "1 /x" key or a "x-1 " key, change the settings from standard to scientific, or vice a versa.
Here is an online calculator with the right key.http://calculator-1.com/scientific/