okay. so a couple of problems with this code, although it tests good. Your code doesnt return null when there is a non-character number, it doesnt take into account if the last index of the array is 9 when it is greater than 17 in length. this is the same problem i have been having with this kata. but overall it is good, i think it is a problem with javascript as a whole. I spent hours trying to figure this issue out, and without going about it another way without parsing or using Number() i dunno. But I did use your code as reference. Im just gonna move on cuz this kata is killing me.