Multiplicative Persistence Coderbyte Solution

 Have the function MultiplicativePersistence(num) take the num parameter being passed which will always be a positive integer and return its multiplicative persistence which is the number of times you must multiply the digits in num until you reach a single digit. 

For example: if num is 39 then your program should return 3 because 3 * 9 = 27 then 2 * 7 = 14 and finally 1 * 4 = 4 and you stop at 

Multiplicative Persistence Java

import java.util.Scanner;

public class MultiplicativePersistence {

int MultiplicativePersistence(int num) {

return getMultiplicativePersistence(num, 0);

}

int getMultiplicativePersistence(int num, int count) {

String numStr = String.valueOf(num);

if (numStr.length() == 1) {

return count;

}

int newNum = 1;

for (char c : numStr.toCharArray()) {

newNum *= Integer.valueOf(String.valueOf(c));

}

return getMultiplicativePersistence(newNum, ++count);

}

public static void main (String[] args) {

Scanner s = new Scanner(System.in);

MultiplicativePersistence c = new MultiplicativePersistence();

System.out.print(c.MultiplicativePersistence(39));

}

}

Multiplicative Persistence Python

def MultiplicativePersistence(num):

steps = 0

while num > 9:

snum = str(num)

sdigits = list(snum)

num = 1

for snum in sdigits:

n = int(snum)

num = num * n

steps = steps + 1

return steps

print MultiplicativePersistence(raw_input())

Multiplicative Persistence Javascript

Using the JavaScript language, have the function FirstFactorial(num) take the num parameter being passed and return the factorial of it (ie. if num = 4, return (4 * 3 * 2 * 1)). For the test cases, the range will be between 1 and 18. 

function MultiplicativePersistence(num) {

var sum, loop = 0;

var val1 = num.toString(10).split("");

while( val1.length > 1 ) {

sum = 1;

val1.forEach( function(number) {

sum = sum * number;

});

val1 = sum.toString(10).split("");

loop++;

} ;

return loop;

}

Explanation

The challenge passes a string but it expects us to do Math on it so it needs to be converted to numbers. I will use the base 10 parameter of the toString() function to convert each entry in the array to a Number. Then I am going to multiply each entry in the array to get a total. I will repeat this until my total is a single digit number. The number of times I multiplied is returned as the answer. 

Disclaimer: The above Problem is generated by Coderbyte but the Solution is provided by ShouterFolk.