Luhn Algorithm · Copy of Playground Doc

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Luhn Algorithm (Luhn Check)

Enter the number without the check digit

Number Reversed reverses the digit order using help from

this post⁠

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Digit List splits the digits into a list

Every 2nd Digit ~x2 multiplies every second digit by 2 and subtracts 9 if it's larger than 9

Every Other Digit takes the opposite digits from the previous list

Check Digit

sums the Every 2nd Digit ~x2 list and the Every Other Digit list

divides that result by 10 and takes the remainder

subtracts the remainder from 10

Luhn Algorithm Check Digit

Luhn Algorithm Check Digit

Number

Digit List

Every 2nd Digit ~x2

Every Other Digit

Check Digit

7992739871

1789372997

27649

79797

There are no rows in this table

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