Adding vs multiplying quantities in different units

[jonatanschroeder]

When using Quantity(string) to parse a user-provided string corresponding to a quantity, I'm having a few issues when multiple quantities are set for the same dimensionality but different units. In particular, if a phrase contains multiple quantities for the same dimensionality, they are multiplied instead of added, even though the natural form of that phrase is typically interpreted as an addition.

For example, 20.5 minutes works, 20 minutes + 30 seconds works (and is equivalent), but 20 minutes 30 seconds is parsed as 600 minutes * seconds. Similarly, 6 ft 9 in is converted to 54 ft * in instead of 6.75 ft. Same for 6 ft, 9 in.

Is this by design? Is there a way to cause the parsing to prioritize addition instead of where appropriate, or based on a specific dimensionality (e.g., if dimensionality is length use the interpretation that leads to length)?