Question

Wer:

My number is a 2-digit multiple of 9. The ratio of its units digit to its tens digit is 1:2.
What is my number?

Answer 1

63

Explanation:

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First, let's list all the 2-digit multiples of "9":

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18, 27, 36, 45, 54, 63, 72, 81, 90, 99.

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From this list, the only answer that has a ratio in which its "units digits to its tens digits" is "1:2" is: "63" . "3:6" = "1:2" .

Answer 2

Let's call the tens digit "x" and the units digit "y". We know that the number is a multiple of 9, so:

x + y = 9

and the ratio of the units digit to the tens digit is 1:2, so:

y = 2x

Substituting the second equation into the first, we get:

x + 2x = 9

3x = 9

x = 3

So the tens digit is 3 and the units digit is 2 times that, or 6. The number is 36.