So i thought it works for me but it doesn't let me pass. Looking at various internet sides etc. it seems that some people do not think 3-9 are so called Armstrong numbers: https://pages.mtu.edu/~shene/COURSES/cs201/NOTES/chap04/arms.html My output: 4 [1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407] memory 491 time = 0 7 [1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407, 1634, 8208, 9474, 54748, 92727, 93084, 548834] memory 3115 time = 0 But for single digits (>0) it's always x^1 = x. What am i missing here?