BCD addition of three digit numbers

Question

9999+3578

 1 0 0 1   1 0 0 1   1 0 0 1   1 0 0 1
+0 0 1 1   0 1 0 1   0 1 1 1   1 0 0 0

I don't know how to perform addition for larger numbers.

 1 0 0 1    1 0 0 1    1 0 0 1    1 0 0 1
+0 0 1 1    0 1 0 1    0 1 1 1    1 0 0 0
-------------------------------------------
 1 1 0 0     1 1 1 0  1 0 0 0 0  1 0 0 0 1

This is what i am getting

how to perform bcd addition .cant we it treat it as a normal binary addition ? — Pygirl, Sep 04 '16 at 16:44
but you would get answer like $CF19 (h)$ where h represents hexadecimal — Archis Welankar, Sep 04 '16 at 16:47
See Converting decimal(base 10) numbers to binary by repeatedly dividing by 2 — hardmath, Sep 04 '16 at 16:49
teacher told us to write d binary code for each of the digits — Pygirl, Sep 04 '16 at 17:00
Shortly : if the result (of adding two blocks of 4 bits) is larger than $9$ then add $6$ that's all. — Raymond Manzoni, Sep 04 '16 at 17:00
like i did. if addition is invalid bcd then add 6 to that group — Pygirl, Sep 04 '16 at 17:00
Not really : $9_{(16)}+9_{(16)}=12_{(16)}$ appears valid but $6$ has to be added. You should make clear too if you want an implementation or solve this "by hand" (provide the solution of an exercise). — Raymond Manzoni, Sep 04 '16 at 17:07

score 1 · Answer 1 · answered Sep 04 '16 at 16:40

1

Your problem is that you cant present each digit in binary and sum that up, you need to write down the number as whole in binary, and then sum them up regularly modulo 2.

answered Sep 04 '16 at 16:40

Snufsan

2,125

Modulo $2$ with carries. – hardmath Sep 04 '16 at 16:42
Yeah that's what I obviously meant.... – Snufsan Sep 04 '16 at 16:45
If only the Question's meaning were so obvious! It seems to have mutated into, why can't I treat BCD arithmetic as a subset of binary arithmetic, at least for purposes of addition. The issue comes down to how to perform carries. – hardmath Sep 04 '16 at 16:51
http://www.electrical4u.com/bcd-or-binary-coded-decimal-bcd-conversion-addition-subtraction/
actually the read question is 9999-(-3578) i tried to solve it by using the method given in that website
– Pygirl Sep 04 '16 at 17:05

BCD addition of three digit numbers

1 Answers1