# Typescript Numeric Literal Types X * Y (Multiplication)

1 min readJun 30, 2022

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We have seen how subtraction works

now can we do multiplication?

yes we can, and this is how you do it, method 1:

type CreateArrayWithLengthX<

LENGTH extends number,

ACC extends unknown[] = [],

> = ACC['length'] extends LENGTH

? ACC

: CreateArrayWithLengthX<LENGTH, [...ACC,1]>type Multiplication<X extends number, Y extends number, Z extends number[] = []> =

[...CreateArrayWithLengthX<Y>]['length'] extends Z['length']

?[]

:[...CreateArrayWithLengthX<X>, ...Multiplication<X,Y,[1,...Z]>]type A = Multiplication<526,19>['length'] // 9994

type B = Multiplication<1,48>['length'] // error if 2nd interger exceed 47

method 2:

type CreateArrayWithLengthX<

LENGTH extends number,

ACC extends unknown[] = [],

> = ACC['length'] extends LENGTH

? ACC

: CreateArrayWithLengthX<LENGTH, [...ACC,1]>type Multiplication<X extends number, Y extends number, Z extends number[] = [], V extends unknown[] = []> =

[...CreateArrayWithLengthX<Y>]['length'] extends Z['length']

? V['length']

: Multiplication<X,Y,[1,...Z],[...CreateArrayWithLengthX<X>,...V]>type A= Multiplication<19,526> // 9994

type B= Multiplication<526,19> // 9994

limitation: the product cannot exceed 9999 because the max tuple size is 9999

2nd method is better because the 1st method 2nd integer cannot be larger than 47 (method 1 Multiplication is not tail recursion, but still I was expecting it to error at 50, not 48, hmm…)