PROBE allows you to individually select tiles and place the letters you know throughout the puzzle.
Tap PROBE in the bottom left corner of the letter bank, then INPUT DATA to activate.
Tap any tile to select it, then type. You may continue to select tiles and type letters before tapping ENTER.
Every letter in its correct position locks. Letters that are wrong return to the bank.
Each rejected letter is counted and shown with your result, so a confident placement costs nothing but speculative guesses may add up.
PROBE switches off after every submission.