checkSumModulo11 method
Calculate the Checksum using a modulo 11
Implementation
String checkSumModulo11(String data) {
var sum = 0;
var pos = 10;
for (var c in data.codeUnits) {
sum += (c - 0x30) * pos;
pos--;
}
return String.fromCharCode(11 - (sum % 11) + 0x30);
}