Lost Card

Here we got an image with numbers inside.

First we put the image in the right position with Gimp, so we can read the numbers correctly. Now we got : 538xx10365956729 with xx the two numbers that we must find.

Knowing it's a credit card number, the two lost digits can be found using the Luhn algorithm. We used dcode to found the missing digits and it gave us this list :

5380010365956729
5381910365956729
5382410365956729
5383810365956729
5384310365956729
5385710365956729
5386210365956729
5387610365956729
5388110365956729
5389510365956729

The challenge answer is the 2rd number coming from the bottom :

GREP{5388110365956729}