# Binary multiplier please help

1. Jun 1, 2014

### Jack1

hi all,
new here, so sorry, but how do i make a binary multiplier in multisim?
is there a specific chip... or...?
i need to make an 8 bit x 4 bit multiplier

2. Jun 3, 2014

### skeptic2

Can you create a truth table for a binary multiplier? After you have the truth table, can you create a circuit to produce the same truth table?

3. Jun 3, 2014

### donpacino

How do you multiply 2 numbers in base 10?
you multiply the top number by the first digit of the second number.
you then multiply the top number by the second digit of the second number, and multiply it by 10.
continue as needed.
the add all of the numbers together...

well its the same thing with digital systems.

$\,1110$
x1101
1110*1 (shifted by 0) +
1110*0 (shifted by 1) +
1110*1 (shifted by 2) +
1110*1 (shifted by 3) +

add them together and you get
10110110

that is the simplest conceptual way to multiply digital numbers. now it is not the most efficient way.

Last edited: Jun 3, 2014
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