• Cursor is on units
-> Press left
• Cursor is on tens
-> Press left
• Cursor can't go to hundreds because the value doesn't go that far, heck why don't you max it out instead.
= Value is set to max (50)


Sounds 100% fine to me. On the other hand, if these arrows weren't used to MOVE THE CURSOR, I'd be perfectly ok with them changing the value, but then I wouldn't use arrows, I'd use - on the left and + on the right. Also, I wouldn't put arrows above and under the digit. Those are your cue that you're actually working with position-based adjustment of the value's individual digits, and not the value as a whole.

• Observe
• Apply Proper Logic
• ???
• Profit