 # How computer multiply two numbers.?

suppose i have to perform the multupication 100*100 … so how many multipications are actually performed inside the computers to do this multipication. I searched it on stackoverflow , but i didn’t understand their logic…! help !

Hi va1ts7_100,

Computer use Booth’s algorithms for multiplication , this process is slightly different from we
do normal multiplication there is shifting of bits also . There are many videos at Booth’s algorithm
on youtube and it is easily understandable.

i guess from taking an organisation course that its done in a 32bit register or 64bit register - up to ur ps - , that the two numbers first are converted into binary n digits and then summed up to n times

for more detail of this…you can look CO201 Computer architecture and Organization course
this course generally taught in 3rd semester in B.tech(NITs)…

for multiplication there two major algorithms…

``````*Robertson's Multiplication Algorithm
*Booth's Multiplication Algorithm
``````

these algorithm are really simple just look…you will understand definitely very quick…
it just state forward

here two major operation (here we do multiplication at binary level…like 101*011 )

• compare

• if multiplying bit 1 and 1 result :-1
• if multiplying bit 0 and 1 or 1 and 0 or 0 and 0 result :- 0
• shift

• as we use cross mark ‘x’ for shifting in 3’rd grade multiplication method
here we use bit shifting…

``````  0101
X011

0101
01010
000000

001111
``````

now you got it how simple it is …just same as we do in decimal …computer do in binary…

go through for more detail…

*** Happy coding***

thanks @deepakmourya