## Lost Card
Here we got an image with numbers inside.
![Credit card](https://traboda-arena-69.s3.amazonaws.com/files/attachments/Credit%20Card%20_921c50f8-b7a1-458d-9039-5de7fd7fa1cc.jpeg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIA6GUFVMV6HO3NYL6Z%2F20230407%2Fap-south-1%2Fs3%2Faws4_request&X-Amz-Date=20230407T173932Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=53ed76da20541c97e6aefcee1c5e308e4fd34b1b2a4e720bd5d72cd62a2d82f8) 
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](https://www.dcode.fr/luhn-algorithm) to found the missing digits and it gave us this list : ```5380010365956729538191036595672953824103659567295383810365956729538431036595672953857103659567295386210365956729538761036595672953881103659567295389510365956729```
The challenge answer is the 2rd number coming from the bottom : 
GREP{5388110365956729}