Earlier quoted context omitted.
It gets promoted to a fractional type.
Ok, what would happen if one then multiplies by Math.PI?
* (/ 1 3)
1/3 ; result is a fraction
* PI
3.141592653589793d0
* (* 1/3 pi)
1.0471975511965976d0 ; fraction * fp -> fp
* 9999999999999999999999
9999999999999999999999 ;transparent support for bigints