How to verbalize the correct statement of a measure in mixed units

I want help phrasing the instructions in a math question. The issue is the correct way to express mixed units.

For example, if an answer is “25 inches,” I don’t want to accept “25 inches” or “1 foot 13 inches,” but only “2 feet 1 inch.”

I guess you might say that I want the total number of units to be small as possible. But I don’t think anyone would understand what I meant by that. Similarly, I don't think it would do to say that I want the answer "simplified."

Solution 1:

Simply state:

"Express the answer in feet and inches"

As part of the question. Valid answers could be "25 inches" or "2 feet 1 inch", and with this statement, you eliminate the former.

Anyone who answers with "1 foot 13 inches" simply misunderstands how units work. It’s like saying "twenty-thirteen" when you mean thirty-three. Or expressing "2 hours 30 minutes" as "1 hour 90 minutes".