Multiply two numbers

Question

Input: Two decimal integers. These can be given to the code in standard input, as arguments to the program or function, or as a list.

Output: Their product, as a decimal integer. For example, the input 5 16 would lead to the output 80.

Restrictions: No standard loopholes please. This is code-golf, answer in lowest amount of bytes wins.

Notes: Layout stolen from my earlier challenge, Add two numbers.

Test cases:

1 2   -> 2
4 5   -> 20
7 9   -> 63
-2 8  -> -16
8 -9  -> -72
-8 -9 -> 72
0 8   -> 0
0 -8  -> 0
8 0   -> 0
-8 0  -> 0
0 0   -> 0

Or as CSV:

a,b,c
1,2,2
4,5,20
7,9,63
-2,8,-16
8,-9,-72
-8,-9,72
0,8,0
0,-8,0
8,0,0
-8,0,0
0,0,0

Leaderboard

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Answer 1

Clojure, 1 byte

*

:P As a bonus this works on any number of arguments:

[(*)
 (* 2)
 (* 2 3)
 (* 2 3 4)
 (* 2 3 4 5)] => [1 2 6 24 120]

Interestingly you can easily get its source code:

(source *)
(defn *
  "Returns the product of nums. (*) returns 1. Does not auto-promote
  longs, will throw on overflow. See also: *'"
  {:inline (nary-inline 'multiply 'unchecked_multiply)
   :inline-arities >1?
   :added "1.2"}
  ([] 1)
  ([x] (cast Number x))
  ([x y] (. clojure.lang.Numbers (multiply x y)))
  ([x y & more]
     (reduce1 * (* x y) more)))

Answer 2

C# - 11 bytes

(a,b)=>a*b;

Anonymous lambda.

Answer 3

Haskell, 3 bytes

(*)

Call it as a function: (*) a b

or as an operator: a * b .

Answer 4

LOLCODE, 95 bytes

HAI 1.3
I HAS A J
GIMMEH J
I HAS A Q
GIMMEH Q
I HAS A T
T R PRODUKT OF J AN Q
VISIBLE T
KTHXBYE

Try it online!

Answer 5

In Floop, 70 bytes, pos. only

r+s[r-]r[-n?o?s+]r+s-[@[-r-n+]r[s-o-[r-]r[-@;]]]r[n[-r@+r-@+]r[-s+]]s+

I wrote this in three parts:

• Outer part: r+s[r-]r[-n?o?s+]r+s-[A]r[B]s+ (based off of my add-two-numbers program)
• A: @[-r-n+]r[s-o-[r-]r[-@;]] (copies @1 to n, 1 at a time)
• B: n[-r@+r-@+]r[-s+] (copies n to @1 and adds it to @1, 1 at a time)

This forms a loop, until o- is 0 after A runs. Then, @0 is printed.

Try It Online!

Answer 6

Labyrinth, 5 bytes

??*!@

Try it online!

Input format can be almost anything (this simply multiplies the first two decimal integers it finds in the input).

Answer 7

05AB1E, 1 byte

*

Try it online!

Answer 8

FOG, 3 bytes

^^*

Takes input twice and multiplies. I can also just use * and call it a function, but for the sake of uniqueness I decided not to.

Answer 9

Japt, 1 byte

×

Here is a non-1 byte solution

U*V

Run it here

Answer 10

C#, 112 63 bytes

Saved 49 bytes, thanks to milk

a=>b=>{int r=0,i=0,k=0<b?1:-1;for(;i!=b;i+=k)r+=a;return r*k;};

I've already posted an answer using the multiplication operator, but here I do it with a loop.

Answer 11

Math++, 3 bytes

?*?

(Why is there a 30 character minimum?)

Answer 12

Loader, 124 bytes

~A:set B =@IN
~A:set A =@IN
B:~C:decr B
~C:set C =A
C:incr D
C:decr C
set G =0
B:incr G
C:incr G
G:load m
~B:print D
~B:exit

Run from m.ldr, or alternatively replace the m in the third line from the end with the name of the file.

Answer 13

SimpleTemplate, 59 bytes

Since this language doesn't have math (yet), it requires a loop and an increment, to generate the result.

{@setx 0}{@for_ from1 toargv.0}{@incbyargv.1 x}{@/}{@echox}

Ungolfed, with whitespace:

{@set prod 0}
{@for _ from 1 to argv.0}
    {@inc by argv.1 prod}
{@/}
{@echo prod}

---

This answer was written to run on the commit 2166e6bdac44064ec5594d511528d1469ea3feef from 2017-01-07.

On the latest version (commit 9857e4277536555d0b06e8ef9c00ba0c7f23cf6d), one could do like this (50 bytes):

{@for_ from1 toargv.0}{@incbyargv.1 x}{@/}{@echox}

This will show a warning saying that the index 'x' doesn't exist.

---

With a new update (commit 552216290ec0d8cb9893e08d89601c4d67fcc3d1), the code can be written as (21 bytes):

{@set*_ argv}{@echo_}

Answer 14

CJam, 3 bytes

{*}

Try it online!

Answer 15

Cubix, 6 bytes

OI|u*@

This is a slightly different algorithm than the "Add Two Numbers" Cubix solution. It would have been trivial to simply use that solution with a * instead of a + but the flow here is slightly different.

On a cube:

  O
I | u *
  @

rather than using the control flow \ or / and then duplicating I to read in the inputs, I opted to use | to pass over the I twice instead, which forced me to use u to get to the output commands.

The commands are:

• I : read in input
• | : reflect IP left-right
• I : read in input
• * : multiply
• u : do a right-hand u-turn (i.e., two right turns)
• O : output as a number. the IP is now facing North, and has a right turn to make, which takes it to
• * : multiply the top two numbers (essentially a no-op)
• @ : terminate program.

Similarly to the addition solution, the cube's symmetry allows the following solution.

  @
I | U *
  O

Additionally, replacing | with < or T will work as well.

Try it online!

Answer 16

x86_64 machine language (Linux), 5 4 bytes

0:       97                      xchg   %edi,%eax
1:       f7 ee                   imul   %esi
3:       c3                      retq

To Try it online!, compile and run the following C program.

#include<stdio.h>

int f(int a,int b){return a*b;}
const char g[]="\x97\xf7\xee\xc3";

int main(){
  for( int i = 0; i < 10; i++ ) {
    for( int j = 0; j < 10; j++ ) {
      printf( "%d %d %d %d\n", i, j, f(i,j), ((int(*)())g)(i,j) );
    }
  }
}

Answer 17

JavaScript (Node.js), 39 36 bytes

-3 bytes thanks to @MartinEnder

f=(a,b)=>b?b>0?a+f(a,b-1):-f(a,-b):0

Try it online!

This is me having fun , it won't win any competitions but it uses recursion and doesn't use the * operator.

Explanation :

f = (a,b) => {
    if (b == 0) {
        return 0;
    }
    if (b > 0) {
        return(a + f(a , b-1))
    }
    else {
        return(-f(a , -b))
    }
};

Answer 18

√ å ı ¥ ® Ï Ø ¿, 4 bytes

II*o

Almost identical to my answer for the Add two numbers question.

Explanation

I    › Take input from the command line, evaluate and push to stack
 I   › Take another input
  *  › Times the two values together and push to stack
   o › Output the first value on the stack

Answer 19

Intcode, 22 bytes

3,0,3,1,2,0,1,2,4,2,99

Fairly basic. IO boilerplate takes up most of the bytecount, given that the language has multiplication as a builtin (2,0,1,2 would be a valid answer, if snippets were allowed)

Answer 20

International Phonetic Esoteric Language, 4 bytes (WIP language) (OLD)

ɪɪθo

No TIO interpreter yet, but is runnable by cloning the repository above, and calling python3 main.py "code here".

ɪɪθo
ɪ    ; push int
 ɪ   ; push int
  θ  ; pop, pop, push a * b
   o ; pop, print

Answer 21

Brainetry, 257 bytes

Golfed version. A more interesting submission follows.

a b c d e f
a b c
a b c d e f
a b
a b c d e f g h
a b c d e
a b c
a b c d e f g h
a b c d e
a b c
a b c d
a b c
a b c d
a b
a b
a b c d e f g h i

a b c d e f g h
a b c d e
a b
a b
a b c d
a b c
a b c
a b c d e f g h i
a
a b c d e f g h i

a b
a b c d e f g

To try this online, follow this repl.it link, paste the code in the btry/replit.btry file and press the green "Run" button.

Ungolfed version:

This is probably my first Brainetry
program that makes
non trivial use of some of
my new
experimental operators that I introduced, expanding the base
brainfuck implementation this is built
upon. We will
see if this made any difference or not.
This program works in a
rather simple way.
First I read inputs.
Then I have
to nest two loops.
One loop,
two loops.
The two loops will be nested, which is nice.

One loop will have me decrement one of
the user inputs, then I
move left,
(not right)
and successively decrement the
cell I'm at.
I do this
and keep accumulating in another cell. If I loop
with
enough dedication, the final result will be stored someplace.

Legend says,
the correct place is the second cell.

Answer 22

Foam, 10 bytes

;# ;# * .#

Try it online!

I'm gonna be using this lang for the next few weeks

;# returns an integer from input.

* is...multiplication.

.# is output.

Answer 23

LOLCODE, 77 bytes

HAI 1
I HAS A a
I HAS A b
GIMMEH a
GIMMEH b
VISIBLE PRODUKT OF a AN b
KTHXBYE

I has a bettr answar cuz I used PRODUKT OF a AN b in da VISIBLE direktly instaed of in an variable !!1!

Try it Online!

Answer 24

Piet, 10 9 codels

Original image

The 2 white codels on the side can be replaced with any color. Most straightforward solution, literally "read 2 numbers, multiply, output", I really don't know why this answer is more complicated.

Update: saved 1 codel by switching from a 2x5 to a 3x3 grid

Answer 25

rusty_deque, 2 bytes

Two variants: one for the left of the deque, one for the right of the deque.

*! # left
*~ # right

Answer 26

Python 2, 14 bytes

lambda a,b:a*b

Try it online!

I feel like this is too much shorter than from operator import*;mul.

Answer 27

Pyth, 4 bytes

M*GH

Defines a function named g, can call it in this way - gn1 n2, where n1 and n2 are the numbers.

Try it here!

Previous solutions using 5 bytes.

*.).Q and *hQeQ.

Answer 28

OCaml, 4 bytes

( *)

The space after the first parenthesis is needed because (* starts a comment in OCaml.

Try it online!

Answer 29

Scala, 2 bytes

_*

This is a curried lambda / anonymous function. To use it, assign it to a variable:

val f:(Int=>Int=>Int)=_*
f(7)(9)                   //returns 63

How it works:

In Scala, the underscore can be used as a shorthand for the arguments.

_*_, for example, is syntactic sugar for (a,b)=>a*b.

Removing the second underscore is treating the method * of the first argument as a function, results in a curried function that multiplies its arguments.

Answer 30

Pushy, 2 bytes

*#

Try it online!

As you might have guessed, * is the multiplication operator, and # prints the result.