ROBERT NUMBER IS BETWEEN 20 AND 32. THE SUM DIGITS IS 10. WHAT IS ROBERT NUMBER? I KNOW ANSWER IS 28 BUT NEED TO KNOW STEP BY STEP HOW TO GET TO 28?

Answer 1

Only one of these numbers has digits that add up to 10.

21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31