What are these number sequences?

Based on the images, here are the number sequences I can see:

 * 1237

 * 3070

 * 50756

 * 39

 * 100

 * 300

 * 20

 * 447

 * 28

Where do they come from?

Based on the visual evidence, the numbers appear to be written on US dollar bills.

Who wrote them and what's theory behind this phenomenon?

It's impossible to definitively say who wrote these numbers based solely on the images. They could have been written by anyone who came into possession of these dollar bills.

As for the theory behind this phenomenon, there isn't one universally accepted or scientifically proven explanation for why people write numbers on currency. However, we can speculate on some possible reasons for Writing Numbers on Currency:

-Tracking Spending or Transactions: Someone might be using the numbers to keep a personal record of how the money was used, perhaps assigning a code or number to a specific purchase or event.

-Lottery or Games of Chance: The numbers could represent lottery picks, bingo numbers, or other numbers relevant to games of chance. People might write them down on readily available items like cash.

 Memory Aids: The numbers could be reminders of dates, phone numbers, codes, or other information the person wanted to jot down quickly.

-Boredom or Vandalism: In some cases, the writing could simply be a result of boredom or a desire to deface the currency, though this seems less likely if there's a pattern to the numbers.

-Superstition or Beliefs: Some people might believe that writing certain numbers on money will bring them good luck or influence their financial situation in some way, though this is not based on any empirical evidence.

-Organizing or Counting: In specific situations, someone handling large amounts of cash might use numbers to help with counting or organizing the bills.

Why is there no single theory?

The act of writing on currency is likely a personal and varied behavior with different motivations for different individuals. Without more context about where these bills were found or any accompanying information, it's difficult to determine the specific reason behind these particular markings.

It's important to remember that defacing currency is technically illegal in many jurisdictions, although minor markings like these are rarely prosecuted.