I have a number machine. I say x gives y if when x goes in, y comes out. For any numbers x and y, by "xy" I mean x followed by y. Here are my two rules.

1x gives x.
For example, 13 gives 3.
If x gives y, then 2x gives yy.
For example, 213 gives 33 since 13 gives 3.

What is a number that gives itself?

(In reply to re(2): Solution by Charlie)

No, that line means the solution.

Because when you combine the statments, you get "21y gives yy", and subtracting a y from both sides, you get "21 gives y", so y must be 21.

When I said 121 gives itself, I mean 121 = x for the second rule. 2 121 = 21 21. I found y, then figured out what x was. Then I could figure out what the number that gives itself.

Posted by Gamer on 2003-06-08 06:56:20