Yes, but in this case, 3.825 gets first parsed as a `Float64`

(and therefore rounded), and only then is it converted to a rational. Depending on the tolerance given to `rationalize`

, one may not always get \frac{153}{40} as one might expect.

This happens to work, because the round-off error caused by the conversion to `Float64`

is compensated by the approximation in `rationalize`

:

```
julia> rationalize(3.825, tol=1e-15)
153//40
```

When decreasing the tolerance, `rationalize`

produces a better approximation of `Float64(3.825)`

, but not of 3.825 itself.

```
julia> rationalize(3.825, tol=1e-20)
538290589893019//140729565985103
```

Whereas for `big"3.825"`

and with the same level of tolerance, `rationalize`

produces the â€ścorrectâ€ť result (which, again, is not guaranteed, but happens to be the case because round-off errors compensate)

```
julia> rationalize(big"3.825", tol=1e-20)
153//40
```