is is the second group. For subtracting 0101 from 0010, borrowing of decimal 10 is taken
from the leftmost group. us 0010 is ‘1100’, 12 in decimal. Subtracting ‘0101’ (5) from it, gives
‘0111’ (7) as shown.
0001 1100 1010 –
0101 0110
0111 0100
ird step
e leftmost group is now 0001. Subtract 0000 from it. us, the fi nal answer is 174 in packed
BCD form.
0001 1101 1010 –
0000 0101 0110
0001 0111 0100
All this shows that BCD subtraction also needs extra care as BCD addition. In computers,
special instructions take care of this.
Example 0.17
Express the numbers 53 and 18 in packed BCD and subtract ...
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