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Sciss/ISBN13_CheckSum.scala

Created October 31, 2021 22:36
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ISBN13_CheckSum.scala
val s = "978-3-9504622-3-"
val s0 = s.filter(_.isDigit)
val u = (s0 zip Iterator.continually(Seq(1, 3)).flatten).map { case (c, m) => c.toString.toInt * m } .sum
val v = u.roundUpTo(10)
val p = v - u // 4
s ++ p.toString // "978-3-9504622-3-4"
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