# how to make a 3 bit multiplier

Discussion in 'General Electronics Chat' started by dangerous, Dec 27, 2010.

1. ### dangerous Thread Starter New Member

Dec 27, 2010
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hi i need some information on how to make a 3 bit multiplier so plz help me?

2. ### Robin Mitchell Well-Known Member

Oct 25, 2009
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But what about multiplication of 3?
So if you have 1001, how do you multiply by 3?

3. ### shteii01 AAC Fanatic!

Feb 19, 2010
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I thought they want 3 bit by 3 bit multiplier, I found 2 bit by 2 bit in the wiki, and 3x3 in some pdf that I did not look at.

4. ### dangerous Thread Starter New Member

Dec 27, 2010
6
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thanks for the help sir but still i can't figure out the logic diagram of the 3 bit multiplier can u help me?

5. ### kubeek AAC Fanatic!

Sep 20, 2005
4,872
863
You have numbers A with bits a2 a1 a0 and B with bits b2 b1 b0.
To multiply them using shift-add, you take a0 AND B, add to that a1 AND B<<1, then add to that a2 AND B<<2. The result is the multiplied number, which will have up to 6 bits, so you need 6bit adder.

B<<2 means left shift by two places, so that b2 b1 b0 becomes b2 b1 b0 0 0.

All this can also be done in a cycle, so that you need just one adder and a pair of registers. Useful for wide numbers.

6. ### dangerous Thread Starter New Member

Dec 27, 2010
6
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can i use 7 segment in this if yes then how and where?

7. ### tom66 Senior Member

May 9, 2009
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We're not going to do all of your homework.

Simply put it will be difficult to do it with 6 bits. The problem is you need to decode the number into tens and ones, which could be tricky.

8. ### dangerous Thread Starter New Member

Dec 27, 2010
6
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no sir i m not doing my homework i m making a 3 bit multiplier in my project thats why i only want a logic diagram and rest of the work i will do myself

9. ### dangerous Thread Starter New Member

Dec 27, 2010
6
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i want it as soon as possible plz help me?

10. ### tom66 Senior Member

May 9, 2009
2,613
215
You have the 3-bit multiplier, why do you need a display? Just output as binary, it will be "good enough" for most cases.

If it's a personal project why do you need it asap? Also, please wait more than 1 minute between posting.

11. ### dangerous Thread Starter New Member

Dec 27, 2010
6
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thank u sir n also thanks for the advice.