Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

@function em_as_string($px-value) {
    $size: $px-value/ 16px;
    @return $size#{em};
}

@function em_as_number($px-value) {
    $size: $px-value/ 16px;
    @return $size*1em;
}

$font-size-string: em_as_string(16px);
$font-size-number: em_as_number(16px);

// ==================================== // 
// type-of($font-size-string) -> string //
// type-of($font-size-number) -> number //
// ==================================== //

p {
  font-size: $font-size-string / 2; // Won't work
  font-size: $font-size-number / 2; // Works nicely
}

SassMeister-output.css

p {
  font-size: 1em/2;
  font-size: 0.5em;
}