Quads tend to be rarer, plus they’re fewer beneficial in a way given that they don’t let you narrow down numerous candidates all at once, but when you see one, it’s truly worth investigating. Fixing solitary squares may convert quads into triples or pairs, so don’t forget about these! Hard https://sudokuhard-hardsudoku32221.dailyblogzz.com/27182099/top-sudoku-hard-hard-sudoku-secrets