Solution – Challenge 35 – Validate 16 Digits Credit Card Numbers through Mod 10 Algorithm

Below is a possible solution to the challenge – Challenge 35 – Validate 16 Digits Credit Card Numbers through Mod 10 Algorithm.

Enter the below formula as Array formula

=MOD(SUM(IF((MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1))*MOD(ROW(INDIRECT("1:"&LEN(A1))),2)
=0,0,MOD((MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1))*MOD(ROW(INDIRECT("1:"&LEN(A1))),2)*2-1,9)
+1)+(MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1))*MOD(ROW(INDIRECT("1:"&LEN(A1)))-1,2)),10)=0

Note – Array Formula is not entered by pressing ENTER after entering your formula but by pressing CTRL+SHIFT+ENTER. If you are copying and pasting this formula, take F2 after pasting and CTRL+SHIFT+ENTER. This will put { } brackets around the formula which you can see in Formula Bar. If you edit again, you will have to do CTRL+SHIFT+ENTER again. Don't put { } manually.

The workbook containing the above solution can be downloaded from Solution – Challenge 35 – Validate 16 Digits Credit Card Numbers through Mod 10 Algorithm.