Subtracting From Left to Right

Subtraction can be done from left to right. You can even start answering while the question is still ongoing.

Example 1

Step 1
  7,896
- 5,2--   (question ongoing)
  2,6--   (answer ongoing)

Step 2
  7,896
- 5,28-   (question ongoing)
  2,61-   (answer ongoing)

Step 3
  7,896
- 5,281   (question done)
  2,615   (answer also done)

Example 2
  8,652
- 5,478   
  3,2(-2)(-6)
  3,174 answer

The answer is done by subtracting digit to digit.
8 - 5 = 3
6 - 4 = 2
5 - 7 = (-2)
2 - 8 = (-6)

3,2(-2)(-6)
From here, apply "All from 9, Last from 10" and subtract 1 from the preceding positive number. Bar above the number indicates negative.
      _ _
3,2 2 6 = 3, 2-1, 9-2, 10-6
3,1 7 4 answer

Example 3
   134
 -  78   
     _ _
  1 4 4   = 1-1, 9-4, 10-4
     5 6 answer

Example 4
  52,485
- 38,347  
   _        _
2 6, 1 4 2   = 2-1, 10-6, 1, 4-1, 10-2
1 4, 1 3 8  answer

Example 5
  654,321
- 345,678   
      _  _ _ _
3 1 1, 3 5 7  =  3, 1-1, 9-1, 9-3, 9-5, 10-7
3 0 8, 6 4 3 answer

"All from 9, last from 10" is applied for negative numbers because these are simply subtracted from base number with zeros.
       _ _
3, 2 2 6  = 3,200 - 26 = 3,174
   _ _
1 4 4  = 100 - 44 = 56
   _        _
2 6, 1 4 2  = 20-6, 1, 40-2 = 141,388
      _  _ _ _
3 1 1, 3 5 7  =  310,000 - 1, 357 = 308,643

#Matamata