I am thinking of a two-digit number.
If I write 3 to the left of my number, and double this three-digit number, the result is 27 times my original number.
What is my number?

If the digits of the answer are A and B, then algebraically AB = 10A+B. Following the rules of the problem, you can get the equation 3AB = 300 + 10A + B. Doubling the right side of the equation, as is requested by the prompt, gives us 600 + 20A + 2B, which equals 27 times the original number, or 27(10A + B). This might get a bit complicated, but once you simplify those equations algebraically, you get the answer of 24.

Another, easier way to solve this would have been to try the problem in the reverse order, checking each answer. 24 = 648/27.

Asked by Ben Jenkins · Last updated 3 years ago · 813 views · SOURCE