13th minute: of course a digit by digit was a loss of time. But in block 4, you already have the 1 and 9 not in column 1.; and you also have a pair of 6 in the middle row right of the 7. So now, 1,6 and 9 not in column 1 of block 4. So, in column 1, 16 in rows 2 and 8, and 9 in row 9. Hence 9 in r2c2, in r8c9, etc. Fairly nice challenge today, I must admit.
13th minute: of course a digit by digit was a loss of time. But in block 4, you already have the 1 and 9 not in column 1.; and you also have a pair of 6 in the middle row right of the 7. So now, 1,6 and 9 not in column 1 of block 4. So, in column 1, 16 in rows 2 and 8, and 9 in row 9. Hence 9 in r2c2, in r8c9, etc. Fairly nice challenge today, I must admit.
23:21 don't understand how 9 come here