solve 

sudoku 
step
1 2
3 4
5 6
7 8
9 10
<home 
explanations: 
this
is step 9


Now c1 has only one cell left for a 2 in c1r1, and a 7 completes Box 1 and c2. c4 also has only one cell free at c4r2 for the missing 2. Box 8 is short of a 3 and a 7 but the existing 7 in c5 decides the placing. Just a 1 to finish off c5 at c5r3. The last two numbers in Box 2 are 3 and 8 and are the opposite of 3 and 8 in Box 1. r2 is short of a 1 and r3 needs a 2 to finish. r1 needs 7 and 8 but the 7 in c9r4 decides the position. 


