I'm trying to make a program that check the ISBN number and sees if it has the correct check digit, if it doesn't have the check digit it will add one.

我试图制作一个程序，检查IS BN号码，看看它是否有正确的校验位，如果没有校验位，它将添加一个。

youdao

Glancing at the bottom, this is pretty arbitrary, but I chose to format my string as follows: % 1f so at the bottom here I'm printing out %.1f, which quick sanity check means print just one digit after the decimal place.

看下这个底部，这个是相当随意的，但我选择把我的字符串格式化成这样：,所以在这个底部我打印输出，提醒一下，这是一个只打印出,小数点后一位的方法。

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The random 18-digit code plus two check digits will have a four-digit prefix added and it will have intelligence in it.

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All that the user needs to do is swipe the card at the existing check-out machine and enter a four digit PIN.

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The lower that two digit number is - like say 05 - the sooner your check gets cut.

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