sd card reading telephone numbers

Hi, I need some help. I have a sd card and I have ten text folders on it and a phone number in each. I need the program to gradually open it and store the numbers in different variables. Did anyone solve this? Thank you

What have you tried ?
Do the folders and filenames have any structure that would lend itself to being programmed ?
Do you know how to open a file and read from it ?

Unsure why folders must be used as storing in a string or data array with separators would be my preferred method


123456,789012,234678, etc.