# I also present you with this, an ever so slightly improved version:
func isArmstrongNumber(n: int): bool =
  var
    total = 0
    exponent = 1
    cache: array[0..9, int]
  let digits = n.float32.log10.ceil.int
  while exponent < n:
    let d = (n div exponent) mod 10
    if d != 0 and cache[d] == 0:
      cache[d] = d ^ digits
    total += cache[d]
    exponent = 10
  n == total