Convert currency using formula

I need a solution to convert the value of a column (which is in Ariary currency) to a column that will record the converted value in US$ and another column that will record the converted value in R$.

I tried using something simple like ({column with value in AR}*0.00023) - this would give the result in US$, however, the value does not match in the end, since 0.00023 is equivalent to 1 AR, but 0.00046 is not equivalent to 2 AR. So I cannot simply multiply by this fixed value. It must be a repeating decimal or something like that. And I don’t know how to work around this.