Then add the next two numbers: 8 + 4 = 12. Write the 2 to the left of the 6, from above, and carry the 1. You now have 26 as the last two digits, right? Right.
Add the next column: 7 + 6 = 13, plus the 1 you carried from above; 13 + 1 =14. Write the 4 to the left of the 2 above, and carry the 1. The three digits now are 426.
Now add the 3 + 1 = 4. Plus the 1 we carried from above; 4 + 1 = 5. The sum of this addition should read: 5426.
To finish the problem, add -7815 and +5426 like this:
-7815.
+5426.
We may 'reverse' the signs for now, the same result as multiplying both numbers by -1 (don't forget we did this) so our problem now looks like:
7815.
-5426. Beginning with the far right column subtract 6 from 5. Borrow the 1 making it; 15 - 6 = 9. Write this as the last, far right digit.
Subtract the next column; 0 - 2. Gotta borrow another 1, this time from the 8 to make it 10 - 2 = 8. Write this to the left of the 9. These two numbers are 89.
Continue with the next column; 8 - 4. Remember we borrowed 1 from the 8 for the above calculation so this is 7 - 4 = 3. Write this 3 down, we have now 389.
The next column gives us 7 - 5 = 2. Combined with the other numbers we have solved for gives us: 2389. But wait, that is NOT our answer. Remember we changed the signs, multiplied by -1, so we MUST do it again to make "all things right with the (math)world".
2389 x -1 = -2389. There you have it Dogbreath. Eh, er, huh, Dogbox. Yeah that's right. You better like this, it took me a long time to type this out. Give me "Best Answer" ok? Yeah, didn't think so....