Finding a Palindrome Based on Jake Harry's Algorithm

Euler4.fs

//Based on Jake Harry's article on generating palindromes http://www.p196.org/papers10.html
open System

let getDistanceFromNextHundred n =
    100 - (n % 100)

let getTensForAddition n =
    Math.Ceiling(float n/ 10.) * 10.
    |> int

let getNewNum n =
    getDistanceFromNextHundred n
    |> getTensForAddition
    |> (+) n

let rec sumDigits n =
    if n = 0 then 0
    else n % 10 + sumDigits(n / 10)

let reverseDigits =
    Seq.unfold(fun x->if x=0 then None else Some(x%10,x/10))
    >> Seq.toList
    >> List.reduce(fun a b ->a*10+b)

let generatePalindrome n =
    let firstDigitSum = sumDigits n
    let newNum = getNewNum n
    let secondDigitSum = sumDigits newNum
    let difference = firstDigitSum - secondDigitSum
    let palindromeHalf = newNum + difference
    palindromeHalf + reverseDigits palindromeHalf

Seq.initInfinite generatePalindrome
    |> Seq.takeWhile (fun x -> x < 999 * 999)
    |> Seq.max

This is producing the wrong result: 920029.