31.5
that is 42
63 How did you get this answer? The tens digit must be six. The ones digit must be half that, therefore three.
91
40
40
that is 42
48.
63 How did you get this answer? The tens digit must be six. The ones digit must be half that, therefore three.
91
23
The answer depends on what the tens digit is greater than, and what the ones digit does then.
16
40
40
If you can ask this question, the answer is obvious. Between the ages of 41 and 49, the only age where the 4 (tens digit) is twice the ones digit is at age 42. Four is two doubled you know....
There are 45 of them.
That means multiply it by 2. If your tens digit is 3, your ones digit is 6.