Binary to Decimal Conversion

Question

I am taking an image file and converting it into binary format. Then I am converting that binary as a decimal format. But according to my algorithm I want to take 50,000 bits at a time following I am explaining my algorithm.

1. Read an image file from any programming language.
2. Convert that into binary format(pure 0's and 1's).
3. Take 50,000 bits at a time and convert it into decimal format(here I am taking only 1000 bits right now)
4. Convert that decimal again into again binary format.

Now problem is:

• How can I take 50,000 bits at time to convert that into binary format
• How will I convert that decimal number to binary again.

Here are 2 demos

• Converting Binary to decimal https://repl.it/IHMY/1
• Converting decimal to binary https://repl.it/IHMY

Thanks