... by: BGH

To Goosen: after basic deterministic steps, after E9 = 5, A9 is 148 & A3 is 245??
How are either "2-digit cells?" Did you leave out a step or 2?

Also your proposed solution, after E9 = 5, "A9=4 ( A3=5 ) Solved" did not produce a solution.

To ALL: this group is unique in fiddling w/ unsolvable grids. I would very much like to learn from each of *YOU*. Cell or unit pairs as a starting point is self evident. However, when you start with triple+ digits in a cell, HOW DO YOU PICK A STARTING CELL?? Goosen's starting grid AFTER E9= 5, has 4 triple digit cells in row A alone! And a grid total of 24 cells with triple digits. ?

... by: Frans Goosens

#669

Combination 2-digits cells

E9=5 No solution, Undo calculation
E9=7 Wrong, Undo calculation
E9=5 No solution, Fixed
A9=4 ( A3=5 ) Solved,

Total solving time is : 41 sec.
Number of logical steps is : 5317

... by: BGH

Basics 27.2 #669
** 3 Step Solution **
7 @ E4 42.0 Solves for all 7’s
1 @ H9 49.4
— Cell Pair,
— Column 9 Triple
2 @ H4 Solution
— Cell Pair
— Row H Triple
— Column 2 Triple

Dieter's solution matches mine

... by: Dieter

#669 - initially populated cells: 22 = 27,2%
No solver used.
basics: %
Strategy: Numbers 5,6,7,9 occur most frequently, combine two cells.
combinations of B6 = (1,3,5,6) and B8 = (3,4,6,7)
5 matrices left after basic checks.
B6 /B8 = 5/6 solves with E1=8.

Optimization:
B6=5 & E1=8 solve.

... by: Serban

# 669 Basics to 22

1. J1=1 & G1=6 solve

2. J1=1 & E2=9 solve

3. Number 6 n=3 e=6 N=18 Nc=11 Ns=4 => E6=J7=6 solve
Note : D3=6