It’s pretty simple: the numeric keyboard used to have letters on them. Now it doesn’t. I used those letters to make words so I could easily remember my pin codes. Now that these letters are gone I’m basically stuck on using the same pin code everywhere because it’s a lot harder to remember a combination of 4 numbers than a 4 letter word. So please, put those letters back. They’re crucial to maintain a secure smartphone.
[FEATURE PROPOSAL] Put the letters back on the numeric keyboard
In the meantime … https://simple.wikipedia.org/wiki/Leet#Leet_for_numbers