Created
September 11, 2020 08:00
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Damm Algorithm check digit for Google Sheets
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// See https://en.wikipedia.org/wiki/Damm_algorithm | |
// =DAMM(5724) == true | |
const cols = { | |
"0": { | |
"0": "0", | |
"1": "7", | |
"2": "4", | |
"3": "1", | |
"4": "6", | |
"5": "3", | |
"6": "5", | |
"7": "8", | |
"8": "9", | |
"9": "2" | |
}, | |
"1": { | |
"0": "3", | |
"1": "0", | |
"2": "2", | |
"3": "7", | |
"4": "1", | |
"5": "6", | |
"6": "8", | |
"7": "9", | |
"8": "4", | |
"9": "5" | |
}, | |
"2": { | |
"0": "1", | |
"1": "9", | |
"2": "0", | |
"3": "5", | |
"4": "2", | |
"5": "7", | |
"6": "6", | |
"7": "4", | |
"8": "3", | |
"9": "8" | |
}, | |
"3": { | |
"0": "7", | |
"1": "2", | |
"2": "6", | |
"3": "0", | |
"4": "3", | |
"5": "4", | |
"6": "9", | |
"7": "5", | |
"8": "8", | |
"9": "1" | |
}, | |
"4": { | |
"0": "5", | |
"1": "1", | |
"2": "8", | |
"3": "9", | |
"4": "0", | |
"5": "2", | |
"6": "7", | |
"7": "3", | |
"8": "6", | |
"9": "4" | |
}, | |
"5": { | |
"0": "9", | |
"1": "5", | |
"2": "7", | |
"3": "8", | |
"4": "4", | |
"5": "0", | |
"6": "2", | |
"7": "6", | |
"8": "1", | |
"9": "3" | |
}, | |
"6": { | |
"0": "8", | |
"1": "4", | |
"2": "1", | |
"3": "3", | |
"4": "5", | |
"5": "9", | |
"6": "0", | |
"7": "2", | |
"8": "7", | |
"9": "6" | |
}, | |
"7": { | |
"0": "6", | |
"1": "8", | |
"2": "3", | |
"3": "4", | |
"4": "9", | |
"5": "5", | |
"6": "1", | |
"7": "0", | |
"8": "2", | |
"9": "7" | |
}, | |
"8": { | |
"0": "4", | |
"1": "6", | |
"2": "5", | |
"3": "2", | |
"4": "7", | |
"5": "8", | |
"6": "3", | |
"7": "1", | |
"8": "0", | |
"9": "9" | |
}, | |
"9": { | |
"0": "2", | |
"1": "3", | |
"2": "9", | |
"3": "6", | |
"4": "8", | |
"5": "1", | |
"6": "4", | |
"7": "7", | |
"8": "5", | |
"9": "0" | |
} | |
} | |
function DAMM(input) { | |
const allDigits = input.toString().split(''); | |
const digits = allDigits.splice(0, allDigits.length - 1); | |
const check = allDigits[allDigits.length - 1]; | |
let rowIndex = "0" | |
for (let colIndex of digits) { | |
rowIndex = cols[colIndex][rowIndex] | |
} | |
return rowIndex === check; | |
} |
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