# Number of allocations
**URL:** https://discourse.julialang.org/t/number-of-allocations/34280
**Category:** New to Julia
**Created:** [February 7, 2020, 3:18am UTC](https://discourse.julialang.org/t/number-of-allocations/34280 "2020-02-07T03:18:49Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@tomtom](https://discourse.julialang.org/u/tomtom)
#### Post date: [February 7, 2020, 3:18am UTC](https://discourse.julialang.org/t/number-of-allocations/34280/1 "2020-02-07T03:18:49Z")
I have difficulties understanding the number of allocations. In the following:
```julia
const v1 = [0, 1]
const v2 = [1, 2]
fun1(x) = begin
a = x .+ v1
return a .* v2
end
fun2(x) = @. (x + v1) * v2
julia> @btime fun1([10, 20]);
102.232 ns (3 allocations: 288 bytes)
julia> @btime fun2([10, 20]);
69.386 ns (2 allocations: 192 bytes)
```
for `fun1()`, one allocation for `a` + one allocation for output, so I think there should be 2 allocations, but in fact there’re 3.
for `fun2()`, only one allocation is needed for output, but in fact there’re 2 allocations.
where is the **extra allocation**? thanks
---
### Author:  [@Mason](https://discourse.julialang.org/u/Mason)
#### Post date: [February 7, 2020, 3:41am UTC](https://discourse.julialang.org/t/number-of-allocations/34280/2 "2020-02-07T03:41:08Z")
Here’s a hint:
```julia
julia> @btime [10, 20]
30.892 ns (1 allocation: 96 bytes)
2-element Array{Int64,1}:
10
20
```
spoiler alert:
You’re allocating memory just by passing the input array. If you don’t want to count that allocation, you need to interpolate the argument into the benchmark macro:
```julia
julia> @btime fun1($([10, 20]));
74.942 ns (2 allocations: 192 bytes)
julia> @btime fun2($([10, 20]));
41.787 ns (1 allocation: 96 bytes)
```