have h3 := Nat.ofDigits_digits b x
x b : ℕ
hb : 2 ≤ b
xpos : 0 < x
h1 : b.digits x ≠ []
⊢ (b.digits x).dropLast.prod * (b.digits x).getLast h1 ≤ x
x b : ℕ
hb : 2 ≤ b
xpos : 0 < x
h1 : b.digits x ≠ []
h3 : Nat.ofDigits b (b.digits x) = x
⊢ (b.digits x).dropLast.prod * (b.digits x).getLast h1 ≤ x