in bijection-core/src/main/scala/com/twitter/bijection/EnglishInt.scala [140:151]
private def fold100(numbers: List[Int]): Int = {
val res = numbers.foldLeft(0, 0)((adderaccum: (Int, Int), b: Int) => {
val (adder, accum) = (adderaccum._1, adderaccum._2)
if (b == 100) {
(0, adder * b)
} else if (b == 1000 || b == 1000 * 1000) {
(0, (adder + accum) * b)
} else
(adder + b, accum)
})
res._1 + res._2
}