Editing Persistence of a number (section)

== Examples ==
The additive persistence of 2718 is 2: first we find that 2&nbsp;+&nbsp;7&nbsp;+&nbsp;1&nbsp;+&nbsp;8&nbsp;=&nbsp;18, and then that&nbsp;1&nbsp;+&nbsp;8&nbsp;=&nbsp;9. The multiplicative persistence of 39 is 3, because it takes three steps to reduce 39 to a single digit: 39&nbsp;→&nbsp;27&nbsp;→&nbsp;14&nbsp;→&nbsp;4. Also, 39 is the smallest number of multiplicative persistence&nbsp;3.