sudoku.day

Hidden single

A digit has only one possible home in a unit. easy

2418151287171615189115158102725191010871111181816172727272727277949137562826841975375326849114672398593258617458719423634951866198354856431
In the tinted row, digit 9 fits nowhere except R9C9. Place it there.

A digit that fits in only one cell of a row, column, or box must go there, even if that cell still shows other pencil marks. Scan each unit digit by digit to spot them.