"11037" is the last message from Sayaka Maizono before she died. This message plays a big part in the first trial in Danganronpa: Trigger Happy Havoc and is also mentioned in Danganronpa 2: Goodbye Despair.
"Sayaka had managed to write "11037" on the wall in blood with the last of her strength before she died"
Sayaka almost killed Leon but he pulled out a Uno reverse card and killed her. Sayaka wrote 11037 so some miraculous ladybug character and his stupid friends could solve the case
Sayaka: "Let me mur-"
Leon:*pulls out a uno reverse card "lol u thought'
Sayaka: "oohh nooo well time to write leons name upside down like 11037