# Julia messes up integer exponents?

**URL:** <https://discourse.julialang.org/t/julia-messes-up-integer-exponents/20773>\
**Category:** Performance\
**Tags:** integer-overflow\
**Created:** [February 14, 2019, 4:19am UTC](https://discourse.julialang.org/t/julia-messes-up-integer-exponents/20773 "2019-02-14T04:19:42Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![rdeits](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rdeits/32/286_2.png) [@rdeits](https://discourse.julialang.org/u/rdeits)\
**Post date:** [February 14, 2019, 4:53am UTC](https://discourse.julialang.org/t/julia-messes-up-integer-exponents/20773/2 "2019-02-14T04:53:19Z")

</div>

Julia uses actual machine integer arithmetic, which means that numbers can and do under- and overflow if you try to perform a computation outside of the range of values that can be represented by such an integer. See [Integer overflow - Wikipedia](https://en.wikipedia.org/wiki/Integer_overflow) for more general explanation.

If you actually need to deal with integers outside the range of a 64-bit Int, then you might want to use Julia’s built-in support for `BigInt` (which is much closer to the way integers behave in Python):

```julia
julia> big(10)^19
10000000000000000000

julia> big(10)^100
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

```

Note that `BigInt`s are substantially more expensive to work with than regular `Int`s (this is part of the reason why basic arithmetic in Python is slower than in Julia). If you want something that will be more efficient than a `BigInt` but without unexpected overflow or underflow, check out `SaferIntegers.jl`:

```julia
julia> using SaferIntegers

julia> SafeInt(10)^19
ERROR: OverflowError: 10^19
Stacktrace:
 [1] ^(::SafeInt64, ::SafeInt64) at /home/rdeits/.julia/packages/SaferIntegers/eMjmj/src/pow.jl:45
 [2] ^(::SafeInt64, ::Int64) at /home/rdeits/.julia/packages/SaferIntegers/eMjmj/src/pow.jl:71
 [3] macro expansion at ./none:0 [inlined]
 [4] literal_pow(::typeof(^), ::SafeInt64, ::Val{19}) at ./none:0
 [5] top-level scope at none:0

```

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