dailysudoku.com

[aakif]

I was stuck in the Sept 4 puzzle at the following point

x49 xxx xx5
x51 x98 3xx
386 xxx 921

825 x49 x1x
694 8x1 25x
173 562 x9x

537 xxx 1x9
4x2 9xx 57x
9x8 xxx x32

Then I draw the puzzle on DailySudoku site and asked for hint. The hint given was R7C6 = 4. I am not able to understand the logic behind this clue.

Can anyone help me and explain the technique used here ???

[chobans]

r1c6 can be 3,6,7
But r3 needs numbers 4, 5, and 7 so those three numbers can only go in r3 in box 2 (r1c4-r3c6). So you can eliminate those 3 numbers from other cells in box 2. So r1c6 can only be 3,6

r8c6 can only be 3,6

So in column 6, 3 and 6 can only go at r1 and r8. So you can eliminate these two numbers in other cells in column 6. So eventhough r7c6 can be 4 and 6, you can eliminate 6 and be left with a 4 only.