// All valid credit card numbers

const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];

const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9];

const valid3 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6];

const valid4 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5];

const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6];

// All invalid credit card numbers

const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5];

const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3];

const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4];

const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5];

const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4];

// Can be either valid or invalid

const mystery1 = [3, 4, 4, 8, 0, 1, 9, 6, 8, 3, 0, 5, 4, 1, 4];

const mystery2 = [5, 4, 6, 6, 1, 0, 0, 8, 6, 1, 6, 2, 0, 2, 3, 9];

const mystery3 = [6, 0, 1, 1, 3, 7, 7, 0, 2, 0, 9, 6, 2, 6, 5, 6, 2, 0, 3];

const mystery4 = [4, 9, 2, 9, 8, 7, 7, 1, 6, 9, 2, 1, 7, 0, 9, 3];

const mystery5 = [4, 9, 1, 3, 5, 4, 0, 4, 6, 3, 0, 7, 2, 5, 2, 3];

// An array of all the arrays above

const batch = [valid1, valid2, valid3, valid4, valid5, invalid1, invalid2, invalid3, invalid4, invalid5, mystery1, mystery2, mystery3, mystery4, mystery5];

// Add your functions below:

function validateCred(arr){

for (let i = 15; i = 0; i–){

if (i % 2 === 0) {

arr[i] = arr[i] *2;{

return arr[i];

if (arr[i] > 9){

arr[i] = arr[i] - 9

return arr[i];

} else {

arr[i] = arr[i]

return arr[i];

}

}

} else {

arr[i] = arr[i]

return arr[i];

}

}

let sum = 0;

for (let i = 0; i < arr.length; i++){

sum += arr[i];

}

if (sum % 10 === 0 ){

return true;

} else {

return false;

}

```
}
```

console.log(validateCred(valid1));

https://www.codecademy.com/practice/projects/credit-card-checker

The above is my code and a link to the assignment I’m working on.

My code is running, but it is printing out false, so I know it is not performing the beginning if statements correctly; how do I get these to run correctly? My code should be printing true, but it’s printing false (for the first array listed) because it’s not manipulating the values in the array.

For reference,

- Starting from the farthest digit to the right, AKA the check digit, iterate to the left.
- As you iterate to the left, every other digit is doubled (the check digit is not doubled). If the number is greater than
`9`

after doubling, subtract`9`

from its value. - Sum up all the digits in the credit card number.
- If the sum modulo
`10`

is`0`

(if the sum divided by`10`

has a remainder of`0`

) then the number is valid, otherwise, it’s invalid.

This is what my program is supposed to do.