# How calculator calculate?

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#### RRavi

Joined May 4, 2016
10
Hello,
How calculator calculate so fast add sub multiply divide so fast?
Is there any look up table in processor of calculator?

Last edited:

#### recklessrog

Joined May 23, 2013
985
It's all done with smoke and mirrors.

#### RRavi

Joined May 4, 2016
10

how he is doing?

#### RRavi

Joined May 4, 2016
10

#### JWHassler

Joined Sep 25, 2013
289
Look up the history of the CORDIC algorithm

#### RRavi

Joined May 4, 2016
10
what is it?

CORDIC (for COordinate Rotation DIgital Computer), also known as Volder's algorithm, is a simple and efficient algorithm to calculate hyperbolic and trigonometric functions, typically converging with one digit (or bit) per iteration. It is therefore also a prominent example of digit-by-digit algorithms.

#### WBahn

Joined Mar 31, 2012
26,398
Hello,
How calculator calculate so fast add sub multiply divide so fast?
Is there any look up table in processor of calculator?
As a rule they aren't that fast -- they only seem fast compared to a human. For cost and power (long battery life) the processors used by calculators tend to run pretty slow and not have a lot of sophistication. They can throw lots of cycles at a problem and still arrive at a solution fast enough that humans think it was near-instantaneous.

Now, because they ARE slow, the algorithms, such as CORDIC, that have been used have been carefully developed and optimized for performance on resource starved platforms (limited clock speed, limited memory, limited instruction set).

An adder is just what the name implies -- it's a circuit (digital in this context) circuit that takes two inputs, adds them together, and produces the result as its output. Lots of ways to implement an adder depending on what is important in a particular application -- speed, size, cost, simplicity, ....

#### takao21203

Joined Apr 28, 2012
3,702
Hello,
How calculator calculate so fast add sub multiply divide so fast?
Is there any look up table in processor of calculator?

Adder circuit is reverse of subtraction circuit. In fact electronic calculator is quite slow. normally ASIC built around some cpu core.

#### WBahn

Joined Mar 31, 2012
26,398
what is it?

CORDIC (for COordinate Rotation DIgital Computer), also known as Volder's algorithm, is a simple and efficient algorithm to calculate hyperbolic and trigonometric functions, typically converging with one digit (or bit) per iteration. It is therefore also a prominent example of digit-by-digit algorithms.
Now RRitesh, what is the point of just posting the first couple of sentences from a Wikipedia article when you are asked a question. Clearly it is not because you understand what you have posted -- or at least never has been so far.

#### jpanhalt

Joined Jan 18, 2008
11,088
@WBahn Glad you said it, not me. I suspect Billy Mayo's cousin may be around too.

John

#### JohnInTX

Joined Jun 26, 2012
4,627
waitforitmodsareonit

#### RRavi

Joined May 4, 2016
10
2+5 =7 ??
can we do this we digital I.C.?
Adder circuit is reverse of subtraction circuit.

#### odm4286

Joined Sep 20, 2009
265

#### RRavi

Joined May 4, 2016
10
2+5 =7 ??
can we do this we digital I.C.?
I mean in binary
00=0
01=1
10=2
11=3
.............