10's Complement & Direct Subtraction
Two methods for decimal subtraction - both yielding the same result
9's Complement
Subtract each digit from 9. For any digit
d
, its 9's complement is
9 - d
318 → 681 (9-3=6, 9-1=8, 9-8=1)
Minuend:
-
Subtrahend:
Calculate
10's Complement Method
Discard Overflow
Direct Subtraction
Borrow Method