Improve printing of rational number

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 85.58%. Comparing base (ba3697f) to head (26ae5d3).

Files	Patch %	Lines
src/show.jl	0.00%	6 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #58 +/- ## ========================================== - Coverage 86.26% 85.58% -0.68% ========================================== Files 14 14 Lines 757 763 +6 ========================================== Hits 653 653 - Misses 104 110 +6 ``` | [Flag](https://app.codecov.io/gh/JuliaAlgebra/StarAlgebras.jl/pull/58/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaAlgebra) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/JuliaAlgebra/StarAlgebras.jl/pull/58/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaAlgebra) | `85.58% <0.00%> (-0.68%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaAlgebra#carryforward-flags-in-the-pull-request-comment) to find out more.

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