What do these numbers mean in L.A. Noire?

In the first case of L.A. Noire, you track down a man to his apartment who appears to have had his gun stolen and used in a murder. In the apartment, you find a notebook with the homicide detective's name, Floyd Rose:

However, to my knowledge Floyd is only mentioned in passing as having retired by the time Phelps makes it to Homicide.

What is the purpose of the numbers, and does it have any bearing on the overall plot of L.A. Noire?

Solution 1:

Your partner Dunn tells Phelps that they can either get a commendation or risk their career in pursuit of finding out why Rose's name is in the book. Phelps chooses to just leave the book behind so therefore it is unknown what the numbers mean or why Rose's name is in the notebook though the main point is hinting that Floyd Rose is corrupt and let you wonder what is the meaning.

Most common interpretation is that Floyd owed Schroeder money, hence the date and the amount, and instead of paying him, framed him for murder as to lock him up. The 50 could be 50 dollars, which was a substantial amount of money back then.