# Factor() function not defined error

**URL:** https://discourse.julialang.org/t/factor-function-not-defined-error/4768
**Category:** General Usage
**Created:** [July 10, 2017, 4:58pm UTC](https://discourse.julialang.org/t/factor-function-not-defined-error/4768 "2017-07-10T16:58:54Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![ephemeris](https://avatars.discourse-cdn.com/v4/letter/e/a9adbd/32.png) [@ephemeris](https://discourse.julialang.org/u/ephemeris)
#### Post date: [July 10, 2017, 4:58pm UTC](https://discourse.julialang.org/t/factor-function-not-defined-error/4768/1 "2017-07-10T16:58:54Z")

</div>

There is [factor function](https://docs.julialang.org/en/release-0.4/stdlib/math/?highlight=factor#Base.factor) described in julia docs. However if try it in REPL I get

```julia
>factor(100)
ERROR: UndefVarError: factor not defined

```

If I search docs from REPL i get

```julia
help?> factor
search: factorize factorial Factorization

Couldn't find factor
Perhaps you meant Vector, factorial, factorize, lfact, filter, floor, for, acos, acot, cor, macro or bkfact
  No documentation found.

  Binding factor does not exist.

```

My version is 0.6.0. What is wrong?

---

<div class="post-metadata">

### Author: ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [July 10, 2017, 5:04pm UTC](https://discourse.julialang.org/t/factor-function-not-defined-error/4768/2 "2017-07-10T17:04:04Z")

</div>

You are looking at docs for an old Julia version. Check out the Primes.jl package IIRC.