What number does Winnie's riddle describe? Explain.
Part B
Winnie's friend Marco guessed that her riddle was about the
number 79. Why can't 79 be the answer to Winnie's riddle?
Explain.
Winnie's riddle is: "I am a two-digit number. My tens digit is twice my ones digit. What number am I?" The number that Winnie's riddle describes is 42, as the tens digit (4) is twice the ones digit (2).
79 cannot be the answer to Winnie's riddle because the tens digit (7) is not twice the ones digit (9).